Farnell, Radiospares, Rapid Electronics or CPC should have what you are looking for. Board edge connectors come in all sorts of strange sizes, often greatly dependant on where the board was made. US companies often specify oddball connectors for some reason. It would be a good idea to first find out what the connector is actually called. Farnell will probably be able to advise, as would any of the more knowledgeable lads from MERG which is 'the' model railway electronics group, often to be found at larger model railway exhibitions.
Cheers.
Roy H