Sierra Trading Post has mens for $50 and womens for $40 --- sparse on sizes tho.
I like Vasque trail runners. I have a pair of Velocity's and a pair of Lightspeed's (http://www.rdwngshoestore.com/detail.asp?product_id=7616). I got the Velocity's at the REI garage sale for $20 and the Lightspeeds in a thrift store brand new for $20. I don't think the Lightspeeds are made any more, but they are "sock fit" and the whole upper is just reinforced mesh-- they *breathe*. Bright orange too-- like wearing traffic cones :)