Amazon offers the TP-Link AC1750 Dual-Band 802.11n Wireless PCI Express Adapter, model no. Archer T8E, for $68.89. Clip the $10 off coupon on the product page to cut it to $58.89. With free shipping, that's a buck below our mention from this past spring and the lowest total price we've seen. (It's a current low by $10.) It features 802.11ac WiFi, data transfer speeds of 1,300MB/s at 5GHz and 450MB/s at 2.4GHz, and WPA and WPA2 encryption.