I just purchased 1 gig for $6.25 with shipping added in. This information came from slickdeals.net. The rebate can be found there.
Buy.com has the SimpleTech 1GB Secure Digital Memory Card for $30 - $15MIR - $10 Google Checkout = $5 w/ free shipping.
I hope this is helpful. I can't post URL's because I'm new. I'm sorry for the inconvenience.