Are you meaning a wired network adapter, or a wifi adapter?
Why does it have to be usb over pci-e adapter?
If looking for wifi adapter, have you considered a poweline network adapter? They have a faster real world speed over wifi when 2-3 walls away from the router and the ping/latency is much better then wifi which is what is truly the more important factor for gaming. You can get a tp-link av500 kit for around $30-35 which will be more reliable and better performing then wifi.