Sounds like what you're asking is a question on tax liability, since if you didn't have to pay taxes on your profits, you wouldn't care what your product cost.

I believe the burden is on the taxpayer to prove cost basis with some kind of documentation showing what he paid for it. If there is no proof of what is cost you, the IRS will assign a cost basis of zero and your selling price will be your profit. My knowledge comes from the purchase and sale of capital assets (real estate, stocks, etc.) and possibly there is a different set of rules for a business's stock in trade.

This interpretation does apply to collectibles, like chips and tokens, so keep your purchase records if you are going to be honest and pay your taxes when you sell your collection.