I went through an ordeal over the summer where I traded football cards with a guy ... same deal as you, the communication was great until he got my end (we even agreed to ship on the same day and exchange DC #s), and then I eventually called him out on the boards.
After a few days he came on the boards, totally ripped me and cussed everyone else out, then got banned.
Long story short, I ended up calling the local police department in his township and they showed up at his house — my card had already been listed on eBay, but the officer got there in time, took it from him and sent it back to me unharmed.
Point being, have you considered the authorities?
I don't mean to upset other members who have had good experiences with the guy, but maybe that's what it takes to get him to respond.
I hope it works out for you ... RJ