Camera Lane has a DP1 Quattro in stock, but it's not what you want.
I bought one of the last DP2 Merrills early this year, and I almost regret it. I just can't get images that fully please me like the earlier Sigma cameras.
If you give Camera Lane a buzz, they might know of where to source a secondhand DP1M. There was a secondhand DP2S in the window a couple of months ago.