AFAIK, TI89's are valid on SATI, SATII, and AP tests. However, I've heard they are NOT valid on IB tests, meaning I'm going to have to borrow a cheaper one from a friend. IB only allows up to a TI86.
And damn right $105 is a great price for this calculator. I bought mine at a 20% off Microcenter sale for $120 and thought I got a good deal. If you're a Freshman or Sophomore in high school and plan on taking classes like Pre-Calculus, Math Analysis, Calculus AB, Calculus BC, and AP tests, this is a must have.
Agreed, worms. TI89 can tell you every basic (and most others, too) integral you need to know for HS (and presumably college, though I can't say from experience) classes. I don't NEED to memorize integrals anymore. I know how to do them if I must (like on tests where we have to show work), but why waste my time?
Also, my friend tried to get in on this but, as others have stated, this is a YMMV deal and our local store had it for $150.