Ok, the Trek downthread is a good bike but if you are looking at something speced like that, hit up the Airborne Skyhawk... these guys can throw together a good budget bike!!!
http://www.airbornebicycles.com/prod...2-skyhawk.aspx
the Guardian 9er is in your range:
http://www.airbornebicycles.com/prod...dian-29er.aspx
plus, the $ you save here you can use to buy a good helmet!!!