TigerDirect offers the Samsung Pro 32GB Class 10 SDXC Memory Card, model no. MB-MG32DA/AM, for $21.99 with free shipping. (Amazon offers it for the same price for Prime members.) That's the lowest total price we could find by $3. 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.