nowadays selling fees are too high and the market is flooded with sneakers
best way you'll make money reselling sneakers nowadays is getting them at a discount
If you shipped to a confirmed address and have a tracking number stating the item was delivered at the buyers address you should be good, they'll just hold on to your money for a while. If not then your loss.
eBay cant make money off money orders and they own paypal where they can take an extra 8%(not sure) off your sales.
I believe money orders are illegal in eBay now so its something you have to negotiate with buyers through messages.