If you have no experience in handfeeding a baby bird I do not suggest you get an unweaned baby, too much can go wrong and a reputable breeder will not sell you one either. By waiting until the baby is weaned to bring it home is not going to affect the bonding process as the breeder will be seen as the parent and you will be it's flock member. Most of us here purchased ours after being fully weaned, me included, and they have bonded to us.
I would look for breeders of greys and not in pet stores, you never know where they came from and a breeder can be of a lot of help to a new grey owner.
For breeders in your area have a look at this website:
www.avianbiotech.com