Samsung 64GB Pro UHS-1 Class 10 SDHC Card for $35 + free shipping
Adorama via eBay offers the Samsung 64GB Pro UHS-1 Class 10 SDHC Memory Card, model no. MB-SGCGB/AM, for $34.95 with free shipping. That's the lowest total price we could find by $15. It features up to 80MB/s read speed, and up to 40MB/s write speed.
2 very similar deals were also reported by some other sources: