Thanks to the wonders of mass production and modern printing press, a deck of tarot cards and a guide book cost very little these days. It makes sense they would be quite a bit more expensive before those inventions. If the pictures were drawn by a famous artist, it could already raise the price quite a bit. It would be a lot of work to carve the plates for the press as well, considering there are dozens of cards, each unique. Assuming the cards are coloured, it would mean at least three if not more plates per card. And how many decks do you expect to sell? There are only so many wealthy people in a country. Just buying a single deck might be all they will ever purchase, per household. Yeah, the more I write, the more I think the bulk of the cards are black and white. Still an expensive affair.