I've posted this back in May, but it's important for game makers.
This time, I'll tag @Orteil
Anyways, buying 50 of something just multiplies the normal price by 50, instead of adding to the percent modifier.
BUT, selling 50 is normal?
With this, you can buy 50, sell 50, buy 50, sell 50, and you'll have infinite resources.
For you game devs:
Set your sell price to 0.000001%, or just entirely remove bulk buying (I'm not too sure how to do that, though)