At GameStop, buy two used Nintendo DS games and get a third of equal or lesser value for free. Even better, take an extra 16% off via coupon code "CAG16". If available, opt for in-store pickup to dodge shipping charges, which start at $3.99, or bag free shipping on orders of $24.99 or more via coupon code "SAVER". (Codes don't stack, so be sure to use the one that yields the best discount for your order.) Some exclusions may apply.