I've bought used, barely used, and new. I don't know what the next one will be.
One thing that can be very misleading is the amount that's "saved" by buying slightly used. "New it was $50K and we got it three years old for only $30K!" Sound familiar? That's a 40% savings. You can usually get a 35% to 40% discount off the sticker price on a brand new model. So was that $50K the new sticker price, the price the dealer used when offering a great trade-in price on someone's tired old rv, or was it actually the (discounted) cash value when new?
Some people will actually pay more for a year-old rv (or car, truck, etc.) than they will for the same thing brand new. My late father-in-law, a fanatic about caring for his "good car," traded for a new one every year for $500. The dealer sold his year-old trade-ins for more than they'd sell the same thing new. Weird but true. Buyers wanted that year-old car because it was in pristine condition and was priced a little less than a new one... but they could have gotten a bigger discount on the new one.