Most good bikes will be aimed at the lightweight end of the range and although the frame may be able to take your weight- The anciliaries like forks and wheels will need a lot of maintenance to keep running. One manufacturer that has gone for a "Clydesdale" bike that will take punishment is Kona. They make the Hoss in two forms andd this is a manufacturer that you can trust and the parts are well sorted for the bigger or heavier rider.
UK site is as in the link below but I am certain you can buy cheaper in the US and don't forget that last years models are cheaper.
http://www.konabikes.co.uk/2k7bikes/hoss_2k7.php