I really, really do urge you to take the deposit and find a decent breeder who knows what they are doing and is actually setting their pups up with possible chance of growing up into health, well rounded family pets. Either that or go to a rescue who will help match you up with a dog (or puppy, plenty of them in rescue too) who will be a good fit for you and your existing dog.
Though we got her via a rescue DDog2 obviously originated from a crappy breeder. As well as all the issues she has which were likely caused by being taken from her mum and siblings too young there are other problems which have been as a direct result of her shitty breeding. She developed hereditary cataracts which rendered her blind by the age of only eighteen months old. This was perfectly avoidable had the person who bred her bothered to health test her parents. She needed major surgery (which cost £5000) to restore her sight though it was only moderately successful and she still struggles in low light. She's also predisposed to other eye related conditions as she ages such as glaucoma. She has terrible conformation, so much so it's affected her joints and despite only being medium sized she had bad enough arthritis to require starting daily pain medication when she was only seven years old, no age at all for a dog her size.
That is the sort of thing that happens when people breed without putting any care or effort into it. Some dogs are lucky and despite coming from a crap breeder are healthy and well adjusted. Some, like DDog2, don't and it is a gamble you take if you get a puppy from a bad breeder.
This woman could have chosen to get her dog spayed if she wasn't able to keep her safe from entire dogs. She could have chosen to have an emergency spay for her bitch, or got her the mismate jab. Once she decided the pups were too much for her she could have chosen to approach a rescue for help with the litter and finding homes. Instead she's chosen to allow the pregnancy to continue and chosen to get shut of the puppies too early despite the fact that it's potentially very damaging indeed for them. Even if we give the breeder the benefit of the doubt and believe she only made all these decisions through ignorance it makes zero difference to the potential harm, physically and mentally, that could come to these puppies because of them.
Don't fall into the trap of believing you need to save this puppy. You can do more good by walking away, reporting this breeder (here's the link again of places you can report her to) and getting a dog or puppy from a reputable source. Buying from this person is only going to encourage them to do it all over again, especially given there are clearly buyers willing to take a puppy so young so she doesn't need to bother doing the work she should be doing to get the money for them.