I pick up cartridge variations whenever I see them, provided they're reasonably priced. My favorites are for Colecovison. A few early releases were later re-branded "for Colecovision & Adam" when the Adam computer came out. One of these (Venture) is supposedly very rare, earning a rarity of 9/10 on a list by a respected Coleco authority. I found one in a lot about a year ago - the seller obviously didn't know it was a rare variation. It was an auction, and I won it for $45. The rest of the lot was super common stuff. Someone sold one on Ebay recently, but it's also unlikely he knew it was the rare variation as it was a $9.99 buy it now, and the variation wasn't mentioned in the listing. That one along with mine are the only ones I've ever seen for public sale. Needless to say, it's hard to put a value on it with no specific sales history, although when I shared my buy on AtariAge some collectors said that they would have paid over $100 for mine.