I would definately say no. That deposit is committing you to have a pup and for her to sell you one (which clearly they are happy to do) but for you it's an awfully big risk to take. Pups cost a huge amount these days and reputable breeders will be looking to ensure that all relevant health checks have been done, that pups are as healthy as can be, that pedigrees are compatible and that mother and pups were treated and fed as well as they could and that any prospective buyers are suitable for their pups. You have no idea of any of this and you have never even seen the mother, living conditions, health check records or breeder so until you have, no money should change hands.
I also prefer not to take deposits but do like to see all the prospective family members at least once whilst the bitch is still pregnant if possible but definately a couple of times after birth as it all helps to build up a picture of how well the pup and new family will do together.
I'd walk away and continue your search.
