2-Port USB 3.0 PCI Express Card with NEC Chipset for $12.99 shipped after coupon code MLC1010JN. Here is a screenshot for reference. It is fully compliant with PCI Express Base Specification using NEC Chipset D720200 and has a throughput rate up to 5 Gbps. It also supports simultaneous operation of multiple USB 3.0, USB 2.0 and USB 1.1 devices. It is a pretty inexpensive and easy way to add USB 3.0 capability to a PC.