This deal has ended.
Buy.com has a Kingston 1gb SecureDigital Memory Card 4-Pack for $22.95 after a $19 mail-in rebate valid through 5/12. This breaks down to $5.75 each. Plus, shipping is free and there is no sales tax (except CA, MA, MD, TN). Also, new customers can use this $5 off $50 coupon or new Google Checkout users can signup and get a $10 off discount (you can't get both).