I guess the idea was that if you pulled a denomination card, you could go to your local card shop(remember them?) and trade it for as many Wild Card trading cards as the denomination you had.
In any case, the idea never caught on, and the Wild Card company soon went out of business. Like many cards of that era, they didn't hold a lot of value. However, if you collect cards of a particular player, some of the denominations and varieties can be almost impossible to find.
Along with the different denominations, there are subsets off the base set, such as Running Wild, Force Field and Stat Smashers. Further, among those, there are gold and silver parallels.
Recently I was fortunate to hit upon a lode of '92 Herschel Walker Wild Cards that until now, were blank spaces at the Herschel Hoard.
Here is what I got: The first is one on my top ten most wanted cards list.
1. 1992 Wild Card Field Force 10 Stripe
1992 Wild Card Field Force 20 Stripe
1992 Wild Card Field Force Silver 10 Stripe
1992 Wild Card Field Force Silver 20 Stripe
1992 Wild Card Field Force Silver 5 Stripe
I've been collecting Herschel Walker cards a long time, and to pick up as many of these at once is a rare find. Happy Collecting!