Reforger via Amazon offers Prime members the open-box D-Link AC1200 Dual-Band 802.11ac Wireless PCI Express Adapter for $17.99 with free shipping. (If you don't have a Prime account, be sure to select the option that's not fulfilled by Amazon to score free shipping.) That's $20 under the lowest price we could find for a factory-sealed unit elsewhere. It features two external dipole antennas.