I bought an old RV last year - a 1975 American Clipper. Before that, I had bought a cheap TT. This is what I've learned:
1. Always check the water tanks, lines, etc. BEFORE buying. If the owner won't let you hook up water, don't buy it. Doesn't matter that it's winter and they've "put hoses away due to freeze", etc., if they won't hook up the hose for you don't buy it. They may tell you everything works great, but when you turn on the water and it comes pouring out from under the seat, you know there's something wrong (and replacing hot water tanks can be expensive).
2. Always check the electrical. Turn on lights, water pump, etc. Plug it in to AC power and check the 110 outlets, fridge, air conditioning, etc.
3. Turn on the propane and make sure the stove, hot water heater and fridge work. You may have to fix some leaks, but replacing a fridge is expensive.
3. Don't believe anything the owner/dealer says. If you can't verify it yourself, don't buy it.
4. Buying a decent TT is cheaper than buying a decent RV. $2000 for a TT could get you a decent but used TT. $2000 for an RV will get you at least another $8000 in repair/replacement costs.
My Clipper cost me $4000 and these are the things I've had to do in the past year: replace all tires; replace all fuel lines and filters; replace steering gear box; replace propane tank regulator; replace coil; repair emergency brake; correct mistakes made to rear brakes from prior owner's repair job; replace engine and house batteries; repair charger and add new converter; replace thermocoupler in fridge; replace dump valves (I also had them re-positioned for ease of use). What I still have to do that I know about: rebuild fuel sending unit for front tank; replace all clearance lights; repair leak in heater joint (currently have propane shut off from the heater).
I love my clipper and have not regretted my purchase. But, I knew going in that I was going to be spending money and time every year repairing old worn out parts. Luckily, my problems have been age related and not due to a bad build. Clippers are known for being quality RVs even at 39 years old. Other brands weren't so well built. If you're looking to save money when traveling, this isn't the way to do it.
My last comment is that if you are going to buy an old RV, look for ones that have owners' clubs and a following. It is much easier to find old parts when you have a lot of contacts to help search for you. Many clubs also collect old parts to sell to their members, etc. And they are a huge help when you are trying to diagnose a problem. These clubs are also a good place to get advice before buying - they can tell you what the typical issues are for that RV so you can look for them straight off. You might also find a club owner who is looking to sell and if they are a member of the owner's club, they probably took more pride in and more care of their RV than just JoeBlow off the street.
