By "wheel bearing" I am thinking you mean the hub bearing and if so.......
The one below is on eBay (part number 515058) and cost $105.00 but does not show "National" as the brand name on it as the Rock Auto Parts site one with the same part number (515058) for a higher cost of $230.79 does ????
Rock Auto does have Timken ones for $181.79 SP580310
NAPA wants $304.00 for their BRG BR930416
GM Parts Direct has OEM 15946732 for $291.70
HUMMER-PARTS.COM wants $275.88 plus S&H for theirs. Should be OEM.
Your call I guess. Myself, I'd go with OEM or NAPA but that is just me and others may have other opinions on it.
Good luck, Ed
http://cgi.ebay.com/ebaymotors/HUMMER-H2-03-06-FRONT-HUB-BEARING-515058-NEW_W0QQcmdZViewItemQQhashZitem4a9e7e54b8QQitemZ32 0486659256QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAcce ssories