A bit of additional info:
QCAD is 2D, and pretty powerful for a free program. (The Pro version is also only 2D, but at a very reasonably price, just 33 EUROs.)
Sketchup is 3D. (The Pro version is around $650.00 US.)
SolidEdge offers a free 2D version as well. That has the advantage of having an upgrade path to 3D, if you decided you need it. My understanding is that SE is pretty close to SolidWorks in the way it operates, but I don't have experience with this.
Turbo CAD has various versions that start at around $250.00 or so, up to the full version that is around $1,700.00 US. (The latter includes lots of machinist type stuff, like drawing threads on a bold, with the correct pitch, etc.)