In your price range for class A you generally want to look at a late 90's Fleetwood bounder or a Winnebago adventurer. These are the two I know that are ... ok. Not amazing, but ok. Though I heard a bounder owner swear up and down about his rig at a gas pump. The Adventurer has a lot of safety features the others don't have. Appliances are bolted to heavy steel panels. There is a roll hoop above the driver seat. Yeah it'll still disintegrate if you crash it but the adventurer might give you a slightly better chance of not being killed by a flying microwave. IMHO some other brands like Coachmen are horrendous. There are probably a few other good brands but I don't know them. If I was doing this all over again I would seriously consider a class C though I don't know which brand. They are often cheaper and if you aren't pulling a heavy toad the lighter chassis can help. They aren't always made as well as the class A (with born free being the notable high quality exception). The class C's can be safer due to the steel van front end and you won't have to run the generator to get a/c in the cab while driving in hot weather. They are less safe in that you have a lower driving position so you can't see traffic stopping as easily but they still have a long rv stopping distance. In our old class A winnie the engine A/C just didn't work very well so we always had to run our generator in the hot weather. Look for two roof airs. Look for 50 amp power system if you have 2 roof airs or an energy management system that load sheds. We only had 30 amp so we had to custom wire the rear a/c to a 20 amp cord to be able to use both a/c's at once while hooked up. Class A gas rv's of this vintage have a pretty exceptionally bad ride. I suspect the workhorse (GM) chassis is better because I rememer those having independent coil spring front suspension. Watch out for water leaks. They aren't always terminal on an aluminum frames wall and roof like our Winnebago had, but they have a huge stigma and will hurt your ability to sell. We paid probably a good $5k-6k less for our rig than it would have been worth without the damage. That was passed through when we sold it. It's important to STOP the leaks more than anything else. We patched everything up with eternabond and never had a problem. I didn't know it at the time but the adventurers of that vintage had some unique features that not all of em have. It runs the coolant back to an auxillary heater in the bedroom which is nice. The same coolant also heats the hot water heater tank as you drive. It also had ducted central air which I now consider extremely important. We never had any problem with the coach portion of our winnebago other than leaks - which is pretty good. We had issues with the generator which needed constant tinkering when you changed elevations and the ford chassis part offered a continuous stream of problems.
There are other brands out there like Georgie Boy, Thor, damon, Four Winds, etc. IMHO none of them are as good as the Winnebago. Granted I thought my Winnebago was a real piece of junk but I'm pretty sure it's one of hte best gas Class A's in your price range. Your price range all but dictates no slides.
Seriously consider your finances before attempting this. We paid $12,500 for our Winnebago and in less than a year had to spend $3,000 replacing a head because a warped manifold literally broke a chunk off the Ford 460 head. We also had to replace the manifolds. When doing preventative maintenance we found a quality radiator was over $500 because it was a class A style that had the filler nozzle out front. If we had a class C, we would have been able to use a standard Ford radiator. Accessibility would be much better too. Not to mention air flow which causes the exhaust manifold problem and head replacement to be less likely.
Consider that you will (quite likely) be using this motorhome to travel to areas that have no cell phone reception (let alone other civilization) for close to a 100 mile radius. 100 miles! Makes for a trying experience getting help.
Our motorhome only had 60,000 miles. They aren't quite like cars, and age really hits them hard.
You can find a 1996-1999 Foretravel U270 36' for between $15,000 and $30,000 here and there. Some people want a lot more for the 270's but they aren't really worth it in the end. IMHO this is your best bet. But don't do it. Get your feet wet with a gasser. Save some money for gas and repairs. I don't regret doing that even though I have a $75K foretravel now (well $80K after catching it up on maintenance, and it still needs another $5K in tires). And actually our Winnebago was a good bit more trouble free than the Foretravel has been so far.
Btw, if you are going with a ford chassis you want 1998 chassis (note the chassis is usually 1 year older than the coach). 1997+ has the best E4OD transmission (and it's a good one). 1998+ has the guaranteed updated fuel pump. Aside from a busted cooling hose that fuel pump was our only breakdown. The early Ford V10's shot out the spark plug and stripped the threads in the head (very expensive). 2001+ should be pretty good but those get expensive.
Make sure to get power levelling jacks. Not stabilizing jacks, but levelling jacks. The kind that can pick the whole motorhome up. We were always annoyed by not having them. Big tanks are a plus. Our adventurer had pretty big tanks. 85 gallons fresh water, over 50 gallons black and gray. The adventurer also had crazy storage. More bin storage than our 10 foot longer foretravel.
Ignore any old rooftop satellite dishes. If they even work anymore, they are usually useless for today's receivers (and especially DVR's). Many people rip out the CRT tv's and put in nice LCD tv's. We did that work ourselves and was my first dip into carpentry.
Tires are expensive. Check the date code. Tires should be replaced once they are about 6 years old regardless of tread. You are talking about something that is 10% of the purchase price of your rig so consider it in the price paid.
That's all I can think of for now. The important part of this is to set your expectations accordingly. I drove a 1996 BMW from 125,000 miles to 230,000 miles with very few problems at all. (Still own it, now I race it, same old engine still running). Your 15-20 year old motorhome, even with exceptionally low miles, just won't offer that kind of troublefree service. If you go into it knowing this, you can keep a more positive outlook (and cash on the side to repair it). It's best if you can do your own repairs though since mechanics are pretty expensive and RV and heavy truck mechanics are freaking nuts (seriously, I haven't encountered an actually professional truck service yet). Except maybe Cummins Tampa.
Good luck. Man I wish someone typed ^^^ that out to me when I was sitting where you are ;) That's why I spent the time on it.
Remember too, there may be other good brands. I'm just speaking of my experiences.