You know what I'd pay a fair price for, Dextro-amphetamine. Not Adderall or Dexies, but d-amp powder. It can't be that hard to make, considering it's structural similarity to D-phenylalanine which is really cheap and not watched.
Speed just gets me to wired, I find myself getting overexcited, standing up in my chair when I should be studying. Or the l-amp makes me too anxious which impacts my study. I found about 10-15mg Dexies to be perfect for a long long study session.
You know what's going to be nice and pure, much cheaper, and pretty much the same thing (if not better)? Add a N-methyl group to that molecule.
http://www.forbes.com/sites/jacobsullum/2014/02/20/hyperbole-hurts-the-surprising-truth-about-methamphetamine/