I can imagine the look on the seller's face when I show up with all the gear to test a $250 generator. He'll either suddenly change his mind and say the unit is not for sale or he'll cut a quick deal and say "$50 as is." Home Depot has a new Sportsman 4000-watt propane generator and a Powermate 3250-watt generator for $350 each. Do you think it's worth spending the extra $100 for something new, although I'd be giving up some wattage?
You have to answer that yourself. It depends on what you need to power, how frequently it will be used and for how long. If your area has 7+ day outages every few years then investing in a quiet reliable generator that is miserly on fuel is a good idea. If outages are infrequent and mostly a day or less then a less expensive generator may work just fine. Another thing to think about is service and parts. IIRC, Champion has a decent reputation in the less expensive gennys.
http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/15131645.cfm