How old are the kids? Our kids have traveled in the RV since they were very young. Now that they are a bit older and bigger, the small space and sharing every space (bath, kitchen, seating) with everyone else grates on them after a while. I've met a number of families who started when their kids were 12-15 and the kids just hated the small space.
There is no cheap way to own an RV, and buying something used with the intention of reselling it in a year or so is, IMO, one of the better ways to handle it. Pay attention to vehicle taxes where you live, and please be very careful when you buy. The one way to come out way behind is to overpay for something with very expensive hidden problems. I'd start by trying to find a mobile RV repair service in your area who would be willing to do a pre-purchase inspection.
As an aside, I've met a few foreigners on trips who started with the idea to fly to the US, buy a car or RV, travel for 6 months, and sell it. There's probably some selection bias here, but when I met them they were on the side of the road or in a campground with mechanical troubles because they bought something cheap or didn't take time to select carefully.
Good Luck! We've been across the country a few times with our kids and wouldn't trade the experiences for anything. It's amazing how many fulltimers come up and say something like "I didn't have the time or the money when I was your age, but looking back I really wish I could have traveled more when my kids were home."