First, Prius PHEV's tax
First, Prius PHEV's tax credit will be closer to $2500 than $7500, bringing post-credit price down to $29.5k.
The closest point of comparison to the PHEV Prius is the 2012 Prius Three at $25.5k.
So the PHEV system costs an extra $4k with the subsidy, or $6.5k without. Up to the consumer if they think the plug-in functionality is justified.
If you want to compare Prius vs Camry Hybrid, start with the 2012 Prius Three. $26k, same as the Camry Hybrid LE $26k. Camry is a bit larger, same headroom but 3" extra shoulder room and 3" extra rear leg room. 93.7 cu ft passenger space vs 102.7 cu ft passenger space in the Camry. Prius gets noticeably better fuel economy, at 51/48 mpg vs 43/39 mpg. Prius has a bit more cargo space in the hatch (21.6) vs the Camry Hybrid's 13.4 cu ft in the trunk.
Prius Three also has about $2500 in extra features the Camry Hybrid LE is missing (per truedelta.com):
* Entune ICE system
* navigation and rear camera
* alloy wheels (yes, the $26k camry hybrid has steelies with wheel covers)
I haven't sat in a '12 camry or prius, so it may well be that the interior or the ride in the Camry is nicer. Combined passenger and cargo space is about the same, just the splits are different.
Here's another point of comparison: '12 Prius V. Passenger space is about the same as the Camry Hybrid, cargo space is significantly larger (34 cu ft vs 13 cu ft). Mileage is about the same (44/40 for the V), cost is the same if you compare the Prius V Two to the Camry LE Hybrid (Two drops the navigation and Entune ICE system).