A few things -
That ebay link looks like an imitation of a TP-Link device!
Do you need a 300Mbps device? A 150 Mbps device should be cheaper. Is it compatible with your router / WAP?
Why not get an internal PCI / PCIe wifi card, if you want wifi rather than wired?
If going down the USB route, make sure you get one that has a cable connection to allow the aerial to be located away from the PC - both to improve reception and avoid physical damage. Also allows you to replace it with a better aerial (also applies to internal wifi cards).
I've got one of these:
TL-WN722NC - Welcome to TP-LINK and it works well enough.
SD