Inverted Jenny (position 27) was bought by auction less than 4 months ago for $402,500 and according to Mystic's website they are the one who bought it and are currently selling it for $510,000. Doing the math, they are marking it up just over 26.7 percent more than they just purchased it for.
All they have to do now is sell it. Just cuz they have it priced at $510K doesn't mean they will sell it for that, or that they will sell it quickly. As C3a's go, though, this is a nice one!
On the flip side, 26% markup isn't all that unreasonable. It won't be sold for more (I mean, who's gonna walk up and say, "I'll offer you $525k"?), but it just might sell for less.
If I were seriously in the market for a C3a, I'd keep my eye on all the major auction houses. I'd be personally visiting auctions with a C3a, and bidding on the one I want. If I wanted anonymity, I'd be bidding online. If not, I'd be in the room. I'd have spoken to the auction house weeks earlier to iron out any 'credit' issues. My point is, whoever buys this from Mystic is spending $100k-ish more than necessary. Even if money were NO issue at all, it would still be about the 'game' of the deal. Just the way I am. If I'm not knowledgeable enough to buy a C3a (every one of them has a documented history, so I guess I'm looking for thins/creases/etc like any other stamp I buy) on my own, I guess I'm not buying one. To me, gaining that knowledge is what the hobby is all about.