I'd like to purchase a set of the Ultimate Blackjack Strategy Cards by Don Schlesinger, but have been unable to find them for sale anywhere, including Amazon.

Where might I buy a set of these mystical cards?

I already have a set of the cards from blackjackinfo.com (BJI) -- but I heard that the Ultimate Blackjack Strategy Cards (UBS) also have composition-dependent plays, which the BJI cards don't seem to have. What other improvements do the UBS cards have?

Thanks in advance for any info, and double thanks if dschles happens to see and comment on this.