If you’re curious about 3D printing, you won’t find a cheaper way to get started than this refurbished Monoprice Mini printer, now available for just $120. It comes fully assembled and factory calibrated, so you can throw some files onto the included microSD card and start printing. Its build area is only a 4.7" cube, so you won’t be making massive creations, but you can still have plenty of fun with it.
Note: Don’t forget to grab some filament (linked on the product page).