bitcoinBull, I think it's called an Emporium there, but anyway. The ability of users to offer their own quotes on contracts is being worked upon and will probably be here by Monday. Maybe you give it a spin then.
^ like! But could you explain more? Do you mean writing options? For example, I have 100 bticoins and I write 100 call options at $5.5 and collect the premium, but potentially have to sell my 100 bitcoins if the price increases. How does this work with holding the bitcoins in escrow?
As far as I can tell, no. This means that you can sell options that you've bought from MPOE at prices other than the ones he's willing to buy them back for, and other people can buy yours at your price instead of his. Since he seems to give an infinite supply of options at his price, though, you don't have much flexibility in pricing
Well, that's not really short selling then, if you're only covering a long position.