Purchase and build your own from a kit, or get one already assembled and (nearly) ready to go out of the box.
There are more 3D printer makers showing up all the time. Check out this excellent list of printers and prices. The list stays fairly up to date and can be sorted.
Self-replicating 3D printers (sort of). You also need non-3d printed parts as well. Inexpensive way to get started with your own printer.
A small form factor, low cost, desktop 3D printer that is great for entry level printers. With 12,000 backers it was the largest 3D printer kickstarter ever.
One of the oldest manufactures, and a very popular desktop 3D printer.
The ultimate in 3D printing. The Ultimaker is one of the most advanced desktop 3D printers on the market.