I am very new to skoolies and early on in my build so I could very well be completely wrong but I have done a ton of research for our build and I thought this was a great idea at first as well. The more I read, the more I started seeing this maybe wasn't such a good idea. Most components that come out of RV's aren't necessary the most durable or quality. We are looking to turn our bus into our home so durability and overall quality are big for us. As well as usefulness. Like we have room for a full size kitchen sink, which will be much more user friendly than the shallow rv sink that I was looking at.
You are not wrong, but I still think worth it. The trailer I won bid on went for $350, although with auction fees and driving 10 hrs each way to get it I ended up with about $1k in it.
But.
Pieces I used:
Furnace $350
Water tank $75
Propane plumbing components: $150
Wire, switches, etc: $50
Water plumbing parts: $50
Flatbed trailer: $500
Slide out hardware: $300
Stainless steel sheets $50
Shower fixtures/drain $45
Propane and CO detector ?
Storage bin hatch ?
Fire extinguisher?
Dump tank valves $15
Stuff I have sold or bartered:
Fridge and power converter $500
Aluminum siding recycled $50
Cook top
Sink
Still selling:
Windows
Rooftop ac unit
Water heater
Holding tanks and shower pan were destroyed in incident that totaled trailer.
Trailers and the furniture in them are not robust, but the appliances, plumbing and wiring are pretty much what you would be likely to purchase yourself for your build.
I have found many unexpected ways to make use of the salvaged supplies.
I think it is good to be realistic in expecting your component use to be partial though.