Amazon offers the TP-Link AC1750 Dual-Band 802.11ac Wireless PCI Express Adapter for $68.89. Clip the $15 off coupon on the product page to cut it to $53.89 at final checkout. With free shipping, that's $5 under our mention from last week and the lowest total price we've seen. (It's also a current price low by $15.) It features data transfer speeds of 1,300MB/s at 5GHz and 450MB/s at 2.4GHz, and WPA and WPA2 encryption.