Amazon offers Prime members the Lexar Professional USB 3.0 Dual-Slot Card Reader, model no. LRW307URBNA, for $12.95 with free shipping. (Non-members can spend $35 or more to qualify for free shipping; otherwise, shipping costs $8.22. Adorama and B&H Photo-Video charge the same.) That's the lowest total price we could find by $17. It features read speeds of up to 150MB/s and transfer speeds of up to 500 MB/s.

Update: The price has increased at Amazon; however, Adorama and B&H Photo-Video still offer it for $12.95 with free shipping.