OK here's the thing ..... the 3 lb 6 oz female gave birth to 3 puppies. One was still born and extremely tiny (1 oz)? The second was 3 1/2 oz, still small but normal, and the 3rd one is Flea who's so tiny and fragile. That doesn't seem like a pregnancy and delivery without problems. I know these things can happen in larger moms but they're more prevalent in the tiny moms.
Yes this woman seems to very much care for these pups and their mother demonstrated by waking up thru the night, petting, and sweet talk. What we don't know is it because of $$$ or for the pure love of the breed or maybe a little of both. She does mention that she won't ship Flea and wants him to go to a home that is familiar with yorkies and tinies in particular but she also mentions how much more Flea will cost. Why?
She posted that she has years of vet experience including at UGA but she doesn't say in what position. For all we know she could've been answering phones or cleaning bathrooms.
My point is
ask lots of questions and then think about what your thoughts are on breeding specifically for tinies. Ask her how many moms or babies has she lost breeding. Get a vet reference
for her because she should be asking for one from you. What kind of testing does she do and what are her health guarantees? Good luck.