Depends on the deal. I was shopping for either a KTM300xc or YZ250 when I saw my local dealer slashed the price and I had it for $7k out the door. But there are a ton of good deals on used YZ's out there. Bryon Enns just picked one up for dirt cheap and the bike only had a few hours on it. There are some on Craigslist that pops up once in a while for cheap. Since this bike has been around forever, the aftermarket support is huge. You can make this bike into anything you want.
I just bought a white plastic kit so I can pose a little better.
RM250's are good bikes too. Their engines were copied off the YZ engine and are virtually the same. The good part about the RM is how well it handles. The bad part is the stock clutch is kinda suspect, although my friend went 3 years on one and he's a fucking mad man.