I agree that the discounts offered by Volumebuy are weak. I buy my Marriott gift certificates at 25% discount, and get them within days. If anyone is interested, here's a cut & paste of a post I made a while back:

(1) sign up at ebates.com, which gives cash rebates for purchases at various Internet stores, including 25% at Sparks.com http://www.ebates.com/index.jsp?referrer=betterthanwork
(2) From Ebates.com, enter Sparks.com, a store that sells a bunch of gift cretificates, including Marriott Hotels.
(3) Buy your gift certificate and remember to click the box that entitles you to ClickRewards -- currently 200 for any purchase over $20.

Using this system, if you buy a $50 Marriott gift certificate, you'll get $12.50 cash rebate from ebates.com (25%); 200 ClickRewards miles -- convertible to 200 airline miles or 300 Marriott Rewards points; and, of course, the $50 gift certificate to Mariott.

Good luck all.