If you are handy, you could replace it yourself. The glass lists at $120 at a dealer. Acuraoemparts.com has it for $90.54. You could try finding someone parting out an RL and get a used glass. I had one but sold it last year.
For a tech manual, go to Download PDF PDFTown.com | Free Download PDF and eBook
and search on "acura RL". It is free