What about the HHKB lite model? It's roughly the same price as the apple keyboard, and is a decent quality rubber dome. It might give you layout issues, though.
There are also rubber dome keyboards that look remarkably like the GHSS, such as
this. Free shipping, not that expensive. I had a REALLY old one of these (IR wireless, ps/2) that was actually pretty decent to type on. Admittedly, it was wireless and small, which likely colored my perceptions quite significantly.