Well, for the US, I still go for the Myriad 6 in 1 as the rarest US retail cart, solely because of the cart/box numbering versus the cart totalling that has been dug up on Stadium Events.
You can't go by eBay that much. Well, it can't be the end all be all of making that rarity call. Before the $400 loose SE a year or two back, there wasn't an SE up for a while.... then you could call SE rarer than the panesians. Now, SE is more high profile than it was and the rarity has been adjusted (versus Mike Elter's call, which IS several years old, and passed on time when he saw them pass through his hands). Then you could say the panesians edge out SE.
To get the true rarity, or to make a better assumption, you'd need production values, or some hinting at them. I've heard 5,000 per panesian, but that's more heresay than anything.
And don't forget, the level of rarity that the Myriad, panesians, and SE are at. They are like a tenth of a point apart. 900 vs 2000 (- destructed copies) isn't that much of a difference - compare that Top Gun! (1 million +)
dave