Sinceritytrading via eBay offers the SanDisk Ultra 64GB UHS-I Class 10 microSDXC Card for $16.99 $15.99 plus $1.50 for shipping. That's the lowest price we could find by $2, outside of other eBay sellers. It features transfer speeds of up to 80MB/s.

Note: This item ships from Hong Kong and may take up to three weeks to arrive.