Meritline offers a 20-Pin USB 3.0 Header to Dual USB 3.0 Ports Adapter with PCI Bracket
with free shipping
. That's $5 under the lowest total price we could find for a similar item elsewhere. This adapter plugs into a motherboard's 20-pin USB 3.0 header and adds two rear-panel USB 3.0 ports to an empty PCI opening.
Expect this item to take two to three weeks to arrive.