The commission is 10%, and includes the shipping charge. Make sure you adjust your shipping charge accordingly.

Other pitfalls to watch out for:
You are guaranteeing delivery whether you make the customer pay for insurance or not, so plan a shipping option that includes delivery confirmation.
Sturdy packaging is a must; if a chip arrives broken, eBay will take the refund and give it to the buyer even if you believe the post office is at fault.
Postage rates go up January 17.