Welcome to this great site and the madness that is school bus conversions. I have not had this much fun in years converting our 1988 Crown Super Coach.
To answer some of your questions:
Licensing
First, let's talk about your issues of licensing. In California to drive any bus registered and classified as a bus (even the little mini-buses) you must have a commercial driver's license (CDL). In California that is either a Class A or a Class B. If the bus is 40 feet or less and is legally converted to a motor home and registered with the DMV as such, then you only need a Class C (standard license). However, if the RV is over 40 feet, then you must have a non-commercial Class B license issued by the DMV. You will have to take both a written test and a driving test with the DMV. I don't believe there are any school buses in California that are over 40 feet. So, you should be safe with a standard Class C once you have it converted to a motor home status with the DMV. Unlike some states, there is no weight limit for an RV. My bus gross vehicle weight is over 36,000 pounds. In some states even as a motor home you could not drive it without a special license. Not in California. California cares about the length only for an RV. Caution!!!!! Prior to having it legally registered as a motor home, it will still be considered a bus and you will be in violation of California law if you drive it around without a CDL. The fines can be very stiff if you are stopped and cited for driving without a license. Also, I don't even want to think about what your insurance company would say about covering you if you had an accident while legally unlicensed for that type of vehicle.
Important note. Once you are registered as a motor home, you are exempt from the California Air Resources Board (CARB) requirements on bus diesel engines. Keep in mind this is California and there are no guarantees on how long that will last.
You can haul a trailer behind a converted bus that is registered as a motor home. It cannot exceed 10,000 pounds. There are very complicated exceptions (a farmer hauling stuff within 150 miles of his farm, etc.) that will not apply to most of us. Over 10,000 pounds and you are talking about needing a Non-Commercial Class A California license. Again, written and driving tests apply.
School Bus Type
Everybody has their preferences on school buses in California. 40 feet is the perfect size. That generally means you will be looking for a transit style bus (a flat nose front). There are three types of transit style buses in terms of engine placement: front engine, rear engine (pushers) and mid-ship (under the middle of the bus). The mid-engine style was popularized primarily by Crown Coach which went out of business in 1991. They made some pusher engine Crowns in the late 1980's and early 1990's (almost all Cummins). However, most districts continued to buy the mid-ship engine configuration. They made the best built bus in the United States. They were made like tanks and they would last for decades in regular daily usage as school buses. The oldest school bus in California was just retired a little while ago. It was a 1949 Crown. That tells you they were built to last. They are getting harder and harder to find as they are no longer being made and California is giving school districts grant money to get rid of them since they used those dirty diesel engines. When the school district accepts the grant money, the old Crown is sent to the crusher and can't be sold. The three most popular school bus transits still being used in California are made by Blue Bird, Thomas and International. Almost all of them in California are pushers. I would not recommend a front engine placement for a transit. Pushers and mid-engine buses are much quieter than front placed engines.
Where to Find a Used School Bus
There are a number of places where you can find used school buses:
First Student: They are the largest school bus contractor in the country and they have numerous California divisions. They even have a website devoted to selling used buses. The link is below:
http://www.firststudentinc.com/transpor ... eSupport=1
BusWest: BusWest is a school bus vendor that sells Thomas Bus in California. They take trade-ins from school district and private schools. They sell used school buses. Their website is:
http://www.buswestpreowned.com/
National Bus Sales: National Bus Sales also sells California school buses. Their website is:
http://nationalbus.com/Results.aspx?cat ... ra=0&cdl=1
Creative Bus Sales: Creative is the International school bus dealer in California. They also get trade-ins. Their website is:
http://www.creativebussales.com/used_bu ... le1-cp.php
Craig's List: Craig's List is a good source for finding used school buses. It is amazing the deals you can find on this site.
http://www.craigslist.org/about/sites
A-Z Bus Sales: A-Z is the Blue Bird dealer in California. Again, they get trade-ins. Their website is:
http://www.a-zbusused.com/category/?cat=School
San Diego Unified School District: This site is unusual in that the school district is selling its own buses directly. Many districts pick auction companies to sell their buses (see links below). San Diego is a mild climate and most of their buses are in great shape. Their website is:
http://transportation.sandi.net/fleetsales.html
Public Surplus Web Site: Many school districts use public auctions sites to sell their vehicles. One of these is Public Surplus. Their website is:
http://www.publicsurplus.com/sms/browse/home
InterSchola Site: This company gets much of the surplus property auctions in California's public schools. Check out their site.
http://www.interschola.com/auctions.php ... California
EBay: Of course you can't miss Ebay. That is where I got my 1988 Crown Coach after a furious bidding war with about ten other people. Their vehicle website is:
http://www.ebay.com/motors
Converting Your Bus to an RV
This is a "fun" topic in California. The law says that a former school bus that is converted to a motor home must not be painted "School Bus Yellow" or "similar color." Some states don't care. California does. We originally were planning to paint it some shade of yellow and then decided that a bored California Highway Patrol officer would write us up for the "similar color" to school bus yellow. That would be a huge fixit ticket!!! It can't have its red crossing lights and the lights you place up there can't flash. Any and all school bus type markings (school bus, stop when red lights flash, stop signs, etc.) must be removed. Then you have to make the bus "habitable" defined in California as: "Human habitation is living space which includes, but is not limited to: closets, cabinets, kitchen units or fixtures, and bath or toilet rooms."
You then must submit DMV Form Reg256A (completing the top and then Section E). Section E wants to know the original cost of the bus and the costs of improvements to make it a motor home, including parts and labor.
Some DMV offices demand to see the receipts. Others demand to see the actual bus and come out and inspect the bus to see how "habitable" the vehicle has become and to make sure that the red lights, school bus yellow, and school bus markings have been removed. Others don't seem to care. It is almost guaranteed that if the bus is from out of state, you will have to get a police officer to verify the VIN number.
I just had my bus converted and registered as a motor home in California. I was incredibly lucky and got a DMV clerk who did not want to make my life hell. I even went in without an appointment and left 45 minutes later with new non-commercial license plates, registration costs that were $119 per year as a motor home vs $1,200 per year as a bus, and no requirement to bring the bus in for inspection. That may have been because it was already registered in California as a school bus.
Costs
I paid $6,000 for a 1988 Crown Super Coach with a Detroit Diesel 6-71 turbo and an Allison auto transmission. It was in great shape. Other Crowns in recent weeks have been on the market for as high as $15,000 and a low of $2,500. Blue Birds, Internationals and Thomas transits can be found all over the map in terms of pricing. Low mileage school buses tend to be from school districts vs contractors. Contract buses that are the same age as school district buses can easily have double or more mileage on them than the district bus.
GOOD LUCK on your hunt. You will have a blast and will have memories that will last forever!!!