If you want a perticular chip you can search ebay and watch all of that to see if they are selling and what they are paying. Adjust shipping based on how many chips are sold to the same buyer.

I know this takes alot of work but if you narrow the chips you want you wont look at all chips. I have documented every .50 chip sale for the last 4 years. The prices in general are running less that the current price guides.