If you mean III like roman numeral for package it's three now, they only used roman numerals for 2010. As for price, since you are in SoCal use Dianne at Carson Toyota. She is well known on here, honest and has helped MANY here find and buy their Prius. http://priuschat.com/forums/dealers-pricing/106475-diannes-socal-2012-prius-liftback-inventory.html Look at that thread to see her current inventory or give her a call directly.
Kelley Blue Book That will give you a start but do your research and make dealers compete with each other.
last week got a Prius III w/ 5-pce carpet mats and solar package. Sea Glass Pearl Cash Price = 26200.00 (msrp 28,050.00) there are cars out there don't be afraid to look around a bit