We did speak elsewhere but I might as well go here as well
I know you said additive but I would say look at CNC machines if you are after a bit of quality -- most of the things you will want to make/repair/replace are likely made with techniques similar in terms of what they can remove (3d printers can indeed make things that are impossible to make any other way, hasn't stopped people in the last however many thousand years though), the accuracy/tolerances are far higher, the materials available are far more numerous (3d printers have to heat and extrude, a mill just has to be able to cut away whatever material you stick under it) and they are slightly quicker if you do it right.
Before you hit pro level, or you spend a month* restoring an older one, you have three main classes
Chinese 3020, 6040 engravers made good.
http://www.carving-cnc.com/ (they are all over ebay and amazon)
Roland offerings
http://www.rolanddga.com/products/3d/
That is their lowest end offering, prices are comparable to the 6040 stuff but the machining sizes are considerably smaller and the material range for that is also smaller (you might just be able to worry aluminium, a lot of wood and plastic should be fine though), if you have a bit more cash to throw around then you can do better.
Stuff like shopbot as you head into the fancier range
http://www.shopbottools.com/
There are any number of similar priced tools out there, however I do not know the US friendly vendors of a lot of them so I will leave it at that for the time being.
*example restoration
If you had real money to spend on it and still wanted additive methods then laser sintering is a possibility.
On the quality of the finish then depending upon what plastic it is you can play with a bit of acetone, this guy does it for some of the stuff he was doing