Newegg offers a Microsoft Xbox Live 3-Month Gold Membership for $19.99. Apply coupon code "VCO" and checkout via Visa Checkout to drop the price to $17.99. (Thunderbird Tech via Amazon has it for a buck more.) With free shipping, that's the lowest total price we could find by $7. (We last saw it in April bundled with $15 Xbox Live credit for $25.) Coupon expires August 25.
Note: This coupon can only be applied once per account.