Sounds like a blower motor. Using the posts above, remove the blower motor and spin it with your hand if it binds or makes noise, will need replaced.
Did a quick search on eBay to locate price range and options. Some come as complete kits, others are motor only, no blower wheel. If you are able to remove and attach the blower, you could save some money. GM part for the 03-08 is 88973567:
http://www.ebay.com/sch/i.html?_sop=16& ... _PrefLoc=1" onclick="window.open(this.href);return false;
Napa has the blower with wheel, next day availability in most areas:
http://www.napaonline.com/Catalog/Catal ... 0365960728" onclick="window.open(this.href);return false;
Let us know how it turns out, I am just ahead of you in mileage so it could be just a matter of time...
2005 #10,524 Neptune Vibe "Bandit" Auto, Moon & Tunes 238k

1991 Pontiac Bonneville 3.8L "Granny's Whip" 142k (33nd Anniversary

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