I've noticed the eBay listings for awhile. Some can be hard to search for.
Honestly a thing I would maybe consider, is listing a few of the cards that are in high demand on eBay and have a BIG link to your site in the details of the listing.
Some people here about redemption, but have NO idea where to buy any. Family Christian stores around me quit selling them and the Christian store I used to pick packs up from when I was young has been closed for A LONG time. A few searches on the web will often lead to eBay and Amazon these days. It might be a good advertising to try the eBay scene for awhile.
The Comic book store I used to work at would sell some stuff on eBay. It's advertising and sales wrapped in one, if it's done right.