Actually, you can find an older RV that is in good condition and even low mileage, if you shop around. because they are notorious for getting terrible gas mileage, people do not travel as much in one of the large RV's as they did when gas was much cheaper.
We moved from Idaho to Alabama, and we had several little dogs that we were taking along for the trip; so we started looking for an older RV in drivable condition that could make the trip cross-country.
We ended up with one from the 70's which had less than 50,000 miles on the motor. The people had used it for a week or two in the summers when they went on a family vacation, and a trip up to a nearby campground now and then; so it really had not had a lot of usage, even though it was an older model RV. I don't remember exactly how much we paid for it; but I am thinking it was around $2500. When we got to Alabama, we sold it again, and got most of the money back; so it worked out well for us.
You can also find good bargains on travel trailers, if you do not mind towing something, and have a large enough vehicle to tow a trailer with. Then, you do not have to worry about the engine breaking down somewhere because you are driving your own vehicle that you are comfortable with.
Another option, that would be a compromise between a camper and a tent, is one of those tent camper trailers that folds down to about 2 feet tall, and then opens up into a tent with cooking stove and small bunks inside for sleeping. They are cheap enoug that you could get anew one of these, and it would be more comfortable than sleeping in a tent, and cheaper than an RV.