This is just how Gamestop functions.
They buy sizable quantities of mainstream games that are sure to sell. I.E. Mario, Final Fantasy, Zelda, Pokemon etc because they know these will sell. All the lesser titles like Runefactory and E:WoM they typically count preorders thand then add 1-3 on to that number. In this case I doubt many people preordered Elemental from Gamestop so they were all like "Herp Derp, no preorders. game is bad investment."
Gamestop relies on guaranteed sales from popular franchises and also preorders. Their other half is buying mostly new 50-60$ games for 15$ and selling them for 45-55$ used for months before lowering the price. Doesn't that make you want to hit someone?
TL:DR version - Don't do business with Gamestop if you can avoid it. You're better than that.