Although that's a tall order, it's not impossible. You'll likely be looking at 1999s with 90k+ miles. Still, the potential is there to get a clean, well maintained one for $15k or less.
Check out older Jaycos. They're about as nice a Class C you're going to find for the money (and if you don't care for those, THEN you should consider an older 460 powered unit from the early-mid 1990s)
36ft Damon Intruder Class A - 37ft National Sea Breeze LX Class A
-Past RVs: 19ft Sportsman, 24ft Jayco, 30ft Coachmen Mirada. We had some good times.
"Im a car guy...you've been warned" lol