Have you been to the DMV and talked to them yet? In CO the have a "Dealer Investigators' office that handles stuff like this. When traded my 919 in on my 954, at a local small dealer, I hadnt received my title after a few weeks, couldnt get an answer, finally went over there to find out he had closed shop, and skipped town with the money for all his recent sales. The DMV gave me the # for the Dealer investigator, contacted him, went through the process, in the end it took just over a year, was a pain in the azz, but I got my title no $$ out of pocket. I dont know if they handle private sales the same, but it seems you should check it out if you can.
"He was a wise man who invented Beer"--Plato