i am currently getting a ti 29er made by XACD,, very impressed by the speed they get the modifications on the drawings done, etc, it seems best to get up at 5 in the morning so you can catch them at work,..
i did want the bike in aluminium but xacd had min batch of 500 ,
i also spoke to Lynskey in the US about the ti bike they were up for it and the prototype price wasnt too extrem but they had min order of 15 bikes,, which is too much for me at the moment, as my design is a little bit left field ,,
there is a guy who lives in the next village to me who builds and engineers stuff mainly for racing tricycles but does make normal frames
http://www.trykit.com/ but just looked at his website and he has 6 month waiting list for frames