I may be stating the obvious here, but if you're wanting to buy rather than trade, have you tried bricklink?
Yes, I have looked through the Bricklink listings for these parts. Most are only listed in a few stores and many of these stores are outside the US/have a high minimum purchase. I will get things there if I need to, but I wanted to see if their were any other options.
Also, I am not opposed to trading. If their is interest I will compile a list of some parts I have.