Amazon offers its Prime members the SanDisk Extreme 32GB UHS-I U3 Class 10 V30 microSDHC Memory Card with Adapter, model no. SDSQXVF-032G-GN6MA, for $14.97 with free shipping. (Non-members can spend $49 or more to qualify for free shipping; otherwise, shipping costs $8.) That's the lowest total price we could find by $4. It features read speeds of up to 90MB/s and write speeds of up to 60MB/s. Additionally, it meets the new UHS Speed Class 3 (U3) and UHS Video Speed Class 30 (V30) for 4K UHD video capture at a sustained rate of 30MB/s.

Also available is the SanDisk Extreme 64GB UHS-I U3 Class 10 V30 microSDXC Memory Card with Adapter, model no. SDSQXVF-064G-GN6MA, for $24.99 with free shipping for Prime members. (Shipping adds $8.19 for non-members.) That's also the lowest total price we could find by $4.