I have slot cards from the original Aladdin and from Del Webb's Mint on eBay this weekend. The Mint is the silver card from the 80's that may be the first of the real club cards although it was not read by the machine. See the pic below.

By the way, for those keeping track of the card market, the "Ace of Diamonds" room keys from Desert Inn have sold in the past few weeks on eBay for prices from $75 to $175.