They are very hard to come by (and not helped by the fact that both of my GG nannies had twin males this year!). If you are seriously interested I would suggest you join the GGGS and contact the stock secretary. If you are a member it will be much easier to get in touch with breeders nearby, quite a few people (including myself in there) are now very wary of selling their kids to just anyone asking...
Given the low numbers of breeding GG's I now would only sell to people who I can trust are definitely going to be breeding and registering them too!