By the way, some very good 3D printers are available for under $400. I like the Tevo kits (I have a Black Widow and a Tarantula, but it seems like the Tornado might be the best one currently), but there are several competitors.
The difference in price for a completely assembled and ready to go printer is pretty staggering. The Lulzbot printers are excellent and I use them at our local maker space, but at $2400-ish I think you really need to be committed before you dive in at that level.
Most of the software is free. Fusion 360 has the feel of an engineering 3D CAD program and is free to hobbyists. As I said, I use Google Sketchup (which has a $700 paid version), which is more of a drawing program, but if you use the ruler to establish your own grids you can achieve very precise models. Sketchup has the advantage of being very quick to learn and has lots of community support/addons, which provide a lot of power (for example, internal threads).