I expect that you have tried this. I had the same problem when I first got mine so I silicone sprayed them and worked it into the rubbers with a soft cloth every two or three days for about a month, always replacing the roof in the tightening order specified by Toyota.
The roof no longer leaks, no matter how hard it rains or when I'm cleaning it (I don't use a jet wash though-so that might find it's way in if you use one).
I now silacone the rubbers once every other week, and so far, about 8 months, not one drop of water has got in, dispite the awful weather.
As I said, I expect you have done this but thought it might help to know it can be successful if done diligently.
Good luck with finding the rubbers new, can't really help with that, although you might have better luck looking over the pond as the majority of theirs were aero.