Yes, there is a flat 10% fee for each sale to cover processing costs and service provider fees, but no listing fee or any other hidden fees, and the buyer pays shipping at checkout. So if you sold a $20 shoe, you'd receive $18. The buyer would pay ~$25 or so with tax and shipping.

The prices on products can be 1 of 3 fixed conditions: "Good" ($15), "Great" ($20), and "New" ($25).

Kickflip's payment library is called Fern (based on Square) and is designed around marketplaces, giving users the ability to spend from their current active balance, and it allows the developer to cut and track commissions. Also with Fern the end user has a dashboard they can log into to track their sales, request payouts, etc.