A good paint job will indeed run you somewhere in the $3000 US range to change the color. The body has to be 100% flawless for black, which adds quite a lot to the prep time. To do a color change correctly, the car will need to be almost entirely dissassembled, the paint will need to be stripped to the bare metal and you pretty much end up entirely rebuilding the car. As far as devaluing the car goes, that applies to classic collectables, a six year old Acura is probably already devalued as much as it's going to get (unless you totally rat it our or total it). However, it's not really the kind of car you want to spend the time, money and effort on something as radical and expensive as a color change.
Yes, you can go to one of those cheapie car paint shops. Remember that you do get what you pay for, and I will say I told you so.
-S