Highly recommend you buy this and keep it by your side whenever you consider making a purchase. It has served me better than any other resource.

http://www.amazon.com/gp/aw/d/B0096DNRHK?cache=54af3f6b8702b83fb323039e08461b49#ref=mp_s_a_1_1&qid=1393258438&sr=8-1

Also know that some chips are still being discovered so theres always a chance it is significantly cheaper than listed. Most retailers try to hide these discoveries from collectors knowledge to keep prices as high as they can. Checking completed prices on ebay will be your other best resource. Have fun! Buy what you like, not to make money.