"Why are SoulSilver and HeartGold so expensive??"

I was craving another Johto adventure, so I went to Gamestop's website and looked at SoulSilver and it's going for $45-$55?? What the actual heck? (As of now) You can buy Pokemon X for $15 cheaper than this. The same is for Heartgold. Does anyone have any explanation? via /r/pokemon http://ift.tt/2uVKtcV