Want to buy an XR, looking for advice/reasonable price range.

[Kaneman]

Well it took all of 1 ride on my son's new lil' 110 before I convinced myself I had to have my own. I want to pick up an XR250 in the next month or so, no preference on the year, want it to be in good condition, and titled/registered/street legal. The idea is to teach wifey to ride a motorcycle on it and eventually let her commute to work (speed limit 40mph the whole way), and for me to be able to ride it on the trails with my son.

-What are some things to look for on used XRs that may be model specific?
-What price range am I looking at? See some going on Craigslist like this one: http://dallas.craigslist.org/dal/mcy/2280740632.html , but I can't get an email back so I'm thinking maybe scamola?
-Should I be looking at other bikes to suit those needs?

Thanks dudes/chicas.