My Abby is a chocolate goldendoodle. You can see her pics on my profile. I hear they are rare but at the time I purchased her I didnt know this. It is too bad my breeder didnt advertise herself more - she even had one leftover that was donated to be a seeing eye dog. She is a nice altruistic lady who had also donated part of her profit to the plight in Darfur. But if she advertised on this site that puppy would have been bought up right away. I know she ships all over and Abby has siblings in the USA. If you would like the link to her website friend me and send me an email. You can write her and ask if she plans any more chocolate doodles in the future.
I am not sure about Chocoloate Goldendoodles, but I know 3 people that have Chocolate Labradoodles. Not sure if that is of interest or not. They seem much more common.
First generation chocolate goldendoodles ARE rare and some claim are impossible. That's because for chocolate to occur, BOTH parents must carry the genes for chocolates. Chocolate dogs NEVER EVER EVER have black noses...they have brown or liver noses. Yet, no golden retriever ever has a chocolate nose--their noses are always black (which is dominant).
If a first generation chocolate goldendoodle is to be produced...then the golden retriever has to be carrying a recessive gene for chocolate (which may or may not be possible...but I'm guessing it is possible but not common) so that some pups will come out chocolate.
However, an F1b chocolate goldendoodle is easy because then there are two pairs of poodle genes that can line up so that's why dogs like Abby (who's mom posted above) can exist and it's not really 'rare'. It's just the first generation GD that is rare.