Commuter Needed

MY 2006-2009 is the same car. Some early options became standard later. The only serious recall was the replacement of the inverter coolant pump on 2006-2007. Compared to the earlier Gen2 these have an upgraded display, different texture on the dash, and a less touchy VSC.

 

OP may as well rule out the VW as they're not known for reliability and diesel usually costs more (see http://www.fuelgaugereport.com/ for current averages).

 

If you're using it for commuting only, why will a 2-seater not work for you? Carpool?
It really doesn't matter, because a gently used Prius (G1/2/3) is a helluva good commuting car, and you can haul 4 other PAX if you want to.....and if the three in the back seat are pretty good friends. If you fold up the rear seats, you can even use it for light cargo duty.
As long as you don't need a tow beast, you may want to consider staying a two-car family by trading in one of your other vehicles.
What are you paying for in gas per month, and how much of this do you expect to save by bumping your real world MPG up to the high 40's? What do you consider to be "a ton of money"? How many miles on the commute? What state do you live in? Priuses are more expensive in some markets, and in Northern climes you'll have to consider temperature related MPG dips and/or snow tires. CARB states have higher warranties for some hybrid components (traction battery.)
Priuses have a very light maintenance schedule, and they're pretty reliable, but you'll need to determine whether or not it's been properly maintained, wrecked, flooded, ragged, stolen, etc.
The used Prius market is pretty tight. This means that finding a "gently used" G1,2,3 for "not a ton of money" can be difficult, unless your other two cars have exotic Italian nameplates on them, in which case even a new G3 would not be "a ton of money".
YMMV...