I remember Toyota saying mid 20s, but honestly I think I'd be more willing at 21 or 22. Oh man PA, after seeing your 800+ writeup I just laughed. That's a bit more than I pay on my mortgage. I'm glad I'm not young with insane insurance rates anymore.
Really though, low 20s is the place to be and ridiculously competitive for the market. Option it out if you want to give the kids all the goodies they want and jack your price up that way. That's about how all Scions work. You start getting into upper 20s, and no thanks, I'll buy a Genesis Coupe when the refresh model (rumored 2013) comes out, or a Mustang GT on X Plan.