BuyDig offers this SanDisk Extreme PRO 64GB Class 10 Secure Digital Extended Capacity SDXC Card (pictured), model no. SDSDXPA-064G-A75, for $139 with free shipping ($2.17/GB). That's the lowest total price we could find by $21. It features max read/write speeds of 95MB/s.

Also available is this SanDisk Extreme PRO 32GB Class 10 Secure Digital Extended Capacity SDXC Memory Card, model no. SDSDXPA-032G-A75, for $69.99 with free shipping ($2.19/GB). That's another price low, this time by $15.