I'm confused about this Savannah Cat Breeder?

SBT simply means the cat is a Bengal derived from Bengal parents. It makes no distinction about "quality" and only about parentage. TICA rules specify that the only Bengals that can be shown are SBT (F4's or better) as there is now no reason to introduce the wild cat blood now that the Bengal breeding program is 'stable'. The $650 SBT kitten that's advertised is pet quality, and that's about right for a well-bred but pet quality Bengal. She does offer a health guarantee, requires proof of spay/neuter, keeping indoors, has a waiting list, etc. so does seem pretty legitimate.