Samsung offers its Samsung 64GB Pro Class 10 SDXC UHS-1 Memory Card, model no. MB-SG64D/AM, for $29.99 with free shipping. That's tied with our April mention as the lowest total price we've seen. (It's also a current low by $4.) It features a read speed of up to 90MB/s and 50MB/s write speed. It's also water-, X-ray, magnetic-, and temperature-proof.

Note that this item is currently backordered, however it can still be ordered at this price for delivery when available.