Folding Fixied on Trains

Anyone here ever converted a Raleigh shopper or anything similar to fixed? I have to get on the train once a week and bumming around till 7pm gets me down.

Dahon do a SS folding bike with a coaster brake but I'm not about to buy one for a once a week journey

Agreed that there is a lot of work gone into them expensive folders, hell, I would stretch to a Rohloff if really wanted one but, I get the impression our friend the thread starter was looking for something with a bit less, er, pecuniary impact...