I used Josh Jones. He's in SF and he's awesome! I started out with a 620, and after working with him for a month I got to a 730! He's still a little expensive, but definitely way cheaper than all the major companies. I dabbled with a few and I didn't really like the vibe. Josh was really friendly and felt more like working with a neighbor.
Btw to get back to the original post, a big reason why they don't let you do less than the package deal is because they don't want their tutors to steal the students. Companies take a really big cut, but when you work with an independent tutor, they keep all of it, minus their advertising expenses. I preferred to cut out the middle, go straight to the source, ya know?