Tips for selling. Make a post here in the for sale section. List the transmission type, omitting it or worse lying about the transmission type will be taken as an attempt to hide information about the bus.
List mileage, mileage listed on the ECM is best source, not the odometer. (But that requires equipment to read it so if odometer is all you have, list it instead).
Show many pictures. Pictures of state of inside, (If the inside is livable already then the price you sell for can go way up if it's really completed. If it's just slapstick finished, then don't expect high price for it.) Show many pictures from under the bus front to back. (Even if there's rust underneath, it's still plenty sellable in a lot of cases, but people will feel swindled if they travel to go buy it and find it's a complete rust bucket. Some level of rust is expected so don't worry about showing it if it's there. People just want to gauge what they have to work with before they buy.) Show pictures of the outside body, front back, and both sides. Pictures pictures PICTURES!
Then after all of that, provide a feature set that you've done to it, any historical items you've corrected on the bus (They are old buses people expect some work on them when they buy so listing what was fixed will give buyers peace of mind that they may not have to fix that part).
And finally, List price. You should list your price. A fresh bus running, with original seats in them should go for $2000 - $6000 depending on bus type. Maybe $10000 for a crown. A fresh bus running with demo done to it already should add an extra $2k-$3k to those prices. Demo includes seats removed, skins removed, inside side panels removed, floors removed to bare metal. This is what we call a blank canvas. Some people will pay an extra 2-3k to not have to do the demo stage, some will not. If the bus has amenities, but looks like a 1970's style RV with cheap walls etc, the bus is livable technically, they can go for $15-25k roughly. And if the bus is clean and emaculate, with all amenities, and it looks like a millionaires yacht inside, and engine/transmission re-worked etc, then it goes up to like $60-85k.
A quality build can net you about up to those prices, a quick build is much much lower. And is a large disparity in price between those two. This is what they sell for. Price appropriately.