For $19.95 you get the 'secret' and cards (20 ea for the initial intro w/free shipping).
The refill that you are referring to is for the 3 deck pack. I was told that the deck was 52 cards, but the ad page implies 56 cards/deck (ad says 168 performances in the header). I'll have mine delivered later today and I'll know for sure ;-)
Regardless, whether 52 or 56 cards/decl, this is a great value for 3 decks @$39.95.
For a brief time yesterday, there was an ad page for a single deck, but the pricing was incorrect. I assume that PM is correcting the misprint and will make the page available soon so that single decks may be ordered. I think that the single deck pack is $19.95.
Time will tell...