If you go to http://www.toyota.com/prius/
and enter a zip code the next screen will give an indication of the dealer inventory for that area.
For instance I live in 98221 and the dealer inventory for the Western Washington state area is "limited" with no count of units available. For the 80027 zip (Denver area) the Denver Metro Area inventory is "good" with 50 units available.
However, take it with a grain of salt. I have a son living in the Denver area and the apparent inventory of 8 Prii (Priuses?) at Boulder Toyota got me excited. Since he lives just minutes away from Boulder he drove up to check things out for me. Guess what, all eight cars are spoken for.
He did come back with this info "They sell more Prius than anyplace else in the Rocky Mtn region (7 states) and therefore get the largest allotment of vehicles. The most common option packages out here (Boulder) are #3, #7 and #9."
Since I am looking out to March as a possible delivery date I may cancel my local order and order one from Boulder. HTH (hope this helps)