I would forget about any warranty work and just make sure that what you are looking at is in great shape. If you live somewhere that you can hire an RV Tech, get them to check it out (you will have to pay for them and their time). If you can't locate one, have someone that you know and trust that has an RV get in it and go over it with a fine tooth comb. Get someone that knows appliances to check out the appliances and maybe even a mechanic to check out the brake system and tires. Yes, these may all cost you some $$, but will save you lots down the road.
Open every cabinet and storage space and make sure there are no signs of water damage - remove mattresses and check for any water/insect damage - and then determine whether it's a good deal.
Do lots of comparison shopping on ebay, craigslist, or wherever.
