Walmart offers the Samsung 64GB Evo UHS-I Class 10 microSDXC Card with Adapter, model no. MB-MP64DAT, for $18.74. Opt for in-store pickup to dodge the $4.97 shipping fee. That's a buck under our July mention and the lowest price we've seen. (It's also a current low by $2.) It features data transfer speeds of up to 48MB/s.