My Garmin iQue 3000 cost about 350, it's been since discontinued but it's had successors. It has voice directions and is also a PDA. The touch screen makes it easy to enter in destinations... My only complaints have been a) it kept telling me to stay on the highway I was on when an interchange to switch from express to collector lanes came up (tom tom suffers from this too), b) some how the voice has been deactivated (sound still works) even though it says it's active, c) limited mac support (I can't add maps, have to use a pc for that) d) battery life/battery not user replaceable.
Oh ya, it tells me to drive off a bridge for my route to work...
The model I have is the entry model for the PDA GPS from Garmin and they also have nonPDA versions too (I bought my dad one for christmas a couple years back). I went with the PDA one because of it's ease of use and only cost a little extra then the nonPDA version. Alternatively if your dad already has a bluetooth PDA such as a Treo or WinMobile device there is a low cost blue tooth GPS unit that hooks up to the PDA. Now I don't know if you can receive calls with a smart phone (palm treo, samsung blackjack etc) while using the blue tooth unit or not so that is something to consider/find out before going that route.
The maps are pretty accurate and other then that bridge issue I haven't noticed any issues with routing. It will automatically recalculate a route if you make a wrong turn and has served me well going through ontario and has served my dad well on his cross country trips across canada. Addresses in rural areas may be off a little.
If I were to replace mine I would go with one that had a replaceable battery.
Sites you may consider
www.gpscity.com www.gpscity.ca www.garmin.com
May you live in interesting times.