Remember that 'asking price' isn't 'selling price' on used stuff like RV's. Go look at ones that come close to all your criteria but that are priced 15-20% over your budget. Make a lower offer, start to walk away when it's refused, and see what happens. And be prepared to travel some; I've bought three RV's, and one took going nearly 100 miles, one almost 200.
But inspect and test drive before you buy! Either do both before making an offer, or make the offer conditional on it passing both.
Jim, "The trouble with bucket seats is that not everyone has the same size bucket."