Authorized dealer Roberts Camera via eBay has the Lexar 256GB Professional 3400x CFast 2.0 for $529.00. Compare with a regular price of $675 for this memory card.
This is the older “3400x” version of the card that is capable of 510 MB/s transfer speeds. The newer “3600x” version boasts a slightly faster transfer speed of 540 MB/s but goes for $675.
A large CFast 2.0 card is a huge plus with the new 14 fps EOS-1D X Mark II — shipping soon from Amazon, B&H or Adorama.