yeah i bought it from game to get more points on my card as well. i think you would win if you sue but the effort and cost would really make it a big hassle.
i'd agree with saintly and say to try another game store and if that still doesnt work i would point out that their work practices are unethical.
the reasoning behind their refusal to price match you is 'rediculous!' i saw their stock of mirrors edge on pc that they were trying to sell for $4 and a number of good 360/ps3 titles between $8 and $24.
but really, if they dont like how it works they shouldnt really be in this business. currently in my opinion they are just as bad as EB.