I agree very much with what Tally-Isham and 7Deadly$ins have said so far. Just be very wary, and go into it armed with information. And no, in my experience I don't think it's a common thing for reputable breeders in the US to advertise solely on eBay and other classifieds... I think any good, responsible, established breeder should at least have their own website with information about their cattery, their breeding cats, their health testing, etc. You have to ask yourself, why do you think this person is breeding Bengals? Are they doing it just for the money, or because they strive to better the breed? If they are doing it for the right reasons, they're going to end up spending a lot of money to breed and raise the kittens properly, they're not going to be making money... Breeders who are proud of their cattery and their cats generally have a legit website at the least.
Can you show us links to this person's ads? If not, can you share any pictures they've sent you? If you don't mind me asking, how much is she charging for the kittens? 7Deadly$ins had a good point about making sure you know what to look for in a Bengal kitten, because it's not an uncommon thing for people to try and pass off regular domestic kittens as Bengals or Bengal mixes sometimes.
It's a good thing you're seeking advice before making this commitment, even if it is cutting it a bit close... We are here to help.