I just found a web site that offers mail-in repair for what seem to me to be good prices. It is called Dr. Cell Phone. If I read correctly, the prices quoted include return shipping. The shop is located in Texas, so it would be convenient for anyone in the US.

The link above lists typical prices for N900 repairs. The price for the infamous USB repair seemed to be $50, if I read correctly. (I don't need that repair, if anyone wonders.)