That is a touch question. My advise is ...

If you want the chip, how much you give for it in trade value.
If you have the chip, how much you want for it in trade value.
In reporting sales and auctions, actual prices paid.
If it is in your collection, you could report what you paid for it or what you think it is worth now.

I use the term "trade value" to avoid and implications of sales which would make the site commercial according to the CCGTCC.