My coach is a 2003 three slide. I have been trying to sell it for around that same price and mine has been kept inside its entire life and looks like new inside. That is about the average asking price on those models. I would make an offer of about $40k if I were wanting to buy as the wholesale on that coach is probably less than $35K. Buyer will have to have cash or above average credit as loans on RV's over 10 years old are more difficult to obtain. As far as what to look for.
1. Tires, Look at the date code, 5 to 7 years is the life span. I just replaced mine, $2,800 for Hankooks, $3,600 for Michelins
2. Batteries, it should have at least 2 for the engine and 4 for the house. This is a $500 to $600 cost.
3. Check the service records to make sure it has been maintained. If they don't have them then it's a **** shoot.
4. If the fridge is original then it is about at the end of its life. $4000 for a new one or about $2000 to change to a residential.
5. Check for leaks, soft floor, carpet stains, ceiling stains, wall stains.
6. Check for leaks again.
7. Run the slides out and in several times. Do they go out and in strong or weak. Do they go out and in straight.
8. If transmission has not been serviced then it is time.
9. Check the jacks. Do they work and are there any leaks.
10. Roof, if it has not been serviced then it's time.
11. Shocks, if they are original, time for replacement.
12. Brakes, airbags. Check for wear and leaks.
The list goes on but this will get you started.