Gamestop has map pack vouchers to give out when people purchase the non-game-of-the-year version of Call of Duty 4. I just bought a used copy of CoD4 and they gave me the voucher anyways. This may be YMMV, as I doubt the vouchers are suppost to be given with used games, but make sure you ask for one.
With the 20% off coupon + edge, I got a like-new CoD4 for ~$32 w/ free map pack ($10 value).
With the 20% off coupon + edge, I got a like-new CoD4 for ~$32 w/ free map pack ($10 value).