Welcome, lakers13. Sorry you had to be confronted by bad news almost immediately upon joining the forum, but you are still welcome even if you are unable to walk away from this breeder after it all. Puppies do something both magical and irrational to the best of us… for better or for worse. While I would also urge you to reconsider purchasing from this breeder, I would, frankly, prefer a forum member to be one of her new puppy owners, because at least I know that forum member will have some good support. I agree though that you should get your pup DNA Fanconi tested with OFA (http://www.offa.org) ASAP. It's $65 and it'll help prepare you for your puppy's future, which will hopefully be a long and happy one, regardless of his origins.
All that said, I've also been there/done that with a puppy from an irreputable source. Fanconi is probably the "worst case" scenario related to this breed, but even if the pup tests clear, it's not like everyone's warnings disappear. As an anecdotal example, my adult Shiba was stricken with unrelenting adult-onset allergies, diagnosed with hypothyroidism when he was 6 (which Basenjis are also susceptible to), and has had a pretty difficult, sharp temperament all his life, all of which might have been less of an issue if we had gotten him from a better source. But when he was a puppy, we thought ourselves lucky because he didn't have any "real" health problems. Of course we love him despite his faults. And we were so in love with him after such a short while, there was no way we could have returned him if that was even an option. I think your breeder is counting on that bond to cover her butt if/when something happens to your pup's health further down the road… you sound like you're going through with this because you're ready to take on the responsibility for another living creature, and in that respect, you're already more committed than this breeder sounds like she'll ever be.
So I'm just saying... I'm in no place to judge how "responsible" or "irresponsible" YOU are as a puppy buyer, but puppies bought under less than ideal conditions are going to test you even moreso than the average, already impish little puppy. I think what comes afterwards is going to be the real test. Good luck, and please stick around!