Buy.com has a deal for free (after rebate) 512MB thumb drives through tomorrow (limit two). You'll be charged for the $27 each up front, but you can reduce that by five bucks if you order $50 worth of stuff through this link. Just click on the Hot Deals tab once you get to the site.So, assuming I actually send in the rebate forms (somewhat iffy...), I actually make $5 on the deal, minus postage, and I get 49 miles on my credit card.
Another inexpensive vendor I've found is http://www.vistaprint.com/, which does all sorts of business cards, magnets, calendars, etc. Their posted prices aren't great, but if you get on their mailing list, they'll send you emails with ridiculous discounts pretty frequently. I think I got 250 business cards for like $4, including shipping. Use this link for 30-60% off. Beware, they send three or four emails a week, so if you don't want them clogging your inbox, use a spam account.
1/31/07 Edit: I received an email from Buy.com today saying my stuff shipped even though the site said they were out of stock when I ordered...
2/1/07: Edit: The items came in the mail today. Success! There's another one available here.