I purchased a PrintrBot Jr V2 which both my home-schooling son and I use extensively. We use the excellent and free TinkerCAD web-site for model design.
What's great about 3D printing is the mind-shift. It opens up a new world of what feels possible to do. Here's a project I put together as a Christmas present for my son (http://www.instructables.com/id/Magpi-The-Micro-Arduino-Gaming-Platform-Interface/). I don't think I would have started if I didn't have a precise way to build a case for it, which the 3D printer enabled. The other day my wife wanted hooks for the closet to hang scarves, so I went a designed one to her specifications and printed them. This sounds like no big deal, and in someways it isn't, but on a deeper level it points to a very big shift that's happening. It's a switch away from mass-production consumer culture to micro-self-production. If you want to be in on the ground floor of experimenting and playing in this big shift, and you don't mind the fiddling it takes (because they are finicky machines), then take the plunge.
As far as making money on 3D printing, we've made back the cost of all our filament by printing things for people via makexyz.com and the 3dprintmything subredit. We do this not really for the cash, but as part of the fun of it.
Established technology tends to persist in the face of new technology. -- G. Blaauw, one of the designers of System 360