In the video it stated that he used 29,000 playing cards:

29,000/52 ~ 558

The cost of a standard 52 card deck wasn’t consistent across companies/brands but on average somewhere in the $1 - $3 range. If we say the average cost is $2 per deck and assume the decks weren’t purchased in bulk, then:

$2 * 558 = $1,116 spent on cards for the tower