Julie, it's dangerous to ask about "enlightening".
Here's a link to the auction tracking for the set, in the Yak Shack Price Guide:
http://www.theyakshack.co.uk/tradingcards/index.php?page=cardlist&set=14The scoop is this. When the set first came out, the "short" grass card was provided as an incentive to buyers of 25 cases of the CatCF boxes. It's a "card" but I would almost call it a terrarium. It was sent in a clear 3" x 4" x 2-7/8" tall clear plastic storage box because the movie-used prop material grows right out of the card, to a considerable height.
It's really one of the neatest and/or unique incentives ever issued with a card set. But not to be outdone, Tom Breyer arranged with Artbox to produce an even bigger one for sale exclusively at the New York Toy Fair. The "long" grass card required a 5-1/2" x 4" x 2-7/8" box. Strands of plastic grass from the movie's Chocolate Room extend up to 8" (20 mm).
Based on both scarcity and the "fun factor", these cards are underpriced, IMHO. The average for the last 5 sales tallied at the Price Guide for the short-grass card was US$210, for a card numbered xx/39. Take any other Artbox release with a card limited to 39 copies and it would carry a higher price. Against that, it can't fit into the binder. I still haven't figured out how to store mine long-term, so it sits there on the table ... So I guess I get to "enjoy" it even more than I would otherwise.
The long-grass card originally was BINning for $199.99, but it looks like not enough people knew about it to be looking and bidding. The average for the last 5 sales registered in the Price Guide dropped to US$68. But the card is still a short print, numbered to 95, and the size makes it even more "fun" than the short-grass version.
If you're intrigued by the concept and aren't put off about trying to figure out how to store or display them, I'd say those are good prices. At the very beginning the short-grass incentive card was BINning for $599.99, which is more in line with what you would expect for a #/39 card. The #/30 Pear Tree Leaves from Harry Potter POA typically sells for nearly $2000. But Charlie cards don't have as big a crossover appeal as Harry cards, and it's been quite a while since the movie came out. Against that, the Johnny Depp autograph from the series had 125 copies, and it still brings $400 at auction because Johnny doesn't sign often, and the Freddie Highmore auto (89 copies) is holding steady at about $135. Who knows what these cards are really "worth"?
