Walmart.com has the AT&T $100 Prepaid Wireless Refill Card for $88 + $3 shipping.

The AT&T $100 Prepaid Wireless Refill Card features: Pay as you go with the AT&T $100 Prepaid Wireless Refill. You'll get all the benefits of wireless without the complications — no annual contract, no credit check and certainly no deposit. Simply pay in advance for what you need