Linksys offers its refurbished Linksys Dual Band 802.11ac Mini Wireless USB Adapter for $15.99 with free shipping. That's $11 under the lowest price we could find for a new one, although we saw a refurb for $6 less in March. It features data transfer rates of up to 433Mb/s.

Note: A 90-day Linksys warranty applies.