Seriously, check this one out: the seller claimed to have picked it up at an estate sale, isn't a bassoonist and doesn't know what it is other than a bocal that says Heckel on it, and helpfully points out the crack. Starting price, $100, which sounds like a lot for a cracked corroded old bocal with a busted cork.
But to me it looks like a prewar Heckel bocal, like the ones shown here. These are both prized and a bit rare, worth at least ten times the starting price. I saw one with nice provenance sell on eBay for more than $2000. But the crack? Apparently, those can be repaired. So, a gamble, but not an unreasonable one. I've bought a number of bocals off of eBay, since there are no dealers within a thousand miles of me, and I've been reasonably happy overall. You don't get the experience of trying for the "best" one out of dozens, but you get the feeling of getting a deal, and the chance to play with it extensively before deciding to resell or keep. And this one, it's even reasonable as an investment, if the price doesn't climb too high before the end. If you want it, bid as late as possible, and bid to win. Good luck!
Update: it went for $1125, to a bidder whose first bid was in the last 10 seconds. Ah yes, that too is eBay, the land of broken dreams.