This threw me off at first way back in the beginning but I later learned that it was a good thing. I get that it can be inconvenient at times, especially when there are only a few listings, but look on the bright side; if there are really nothing other than 99 stacks then you have an opportunity to buy one of those stacks, take what you need and then re-sell the remainder that you don't need in smaller quantities at higher prices. That way, people like you who only want a few items and are willing to pay a premium for the smaller stack will skip right to yours, and then, not only did you get what you wanted, you spun a profit from it too.