While sampling beers at the Top of the Hops Beer Festival, I perhaps sampled a few too many and lost the lens bayonet ring from my Ricoh GRD2. I asked around over on the Ricoh Forum, and got some advice on where I could get replacements, but they were various colors and what I really wanted was a plain black OEM ring.
Eventually, I contacted Ricoh and they told me to contact their service facility's parts department - CRIS Camera. They first sent a ring for a GRD3, but I contacted them again and they were very nice and sent the correct ring. After it was all said and done, it cost me $22.00 including shipping. Nice people to do business with.
Here's the contact info.
CRIS Camera Services
480-940-1103 (ext. 101)