I suggest a friendly haggle. $25 (retail) is the at the high-end of price guide value. This means that you can probably get the same chip from most any chip dealer at this same price at most any time.
If you try to haggle, at best you might get a 5 or 10 percent reduction. If you feel that the haggle is worth it, then go ahead. If not, then pass, as you can get it most anytime you really want it, even if you go back to the coin shop.
Keep an eye out on eBay for a month and see if you can do better. If not AND you really like the chip, then go back and get it. However, if you really like the chip already, you will know that you are not over-paying for it.