Apologies for backtracking. We tried this route 2 or so years ago, but ran into a problem. Can't recall the details, but I think it was that the transmission was clipped to only show half the signal (lets say the upper half). This wasn't enough to get the DCC signal through to the decoder. I see that the Americans appear to have solved this, but as they are on different frequencies, and won't sell outside the US, it isn't much help.
Another supplier of radio gear is Malcolm at rpmmodels.co.uk