need some motor home advice

hey guys
long story short, my sister is coming over with her kids for a few weeks, and she wants to rent an RV for a week or so
i was trolling C/L and came across a 94 fleetwood 21 footer RV for 1200 bucks
i figured it might be cheaper to buy it, use it and flip it but i know NOTHING about RVs, so ...good idea?

what should i look for , if i go check it out?

thanks guys
Do you have the listing so we can see what it looks like?
Otherwise all the information given here I got to agree with wholeheartedly. Besides mechanical problems, water leaks are the worst. Mold, yuck.