There are two major types of 3D printers—resin and fused deposition modeling (FDM). Resin printers often have a smaller build area but use liquid resins to create high-quality objects. FDM printers typically have a large build area and use spools of filament to print. FDM printers are notorious for their visible print lines and often need more aftercare to smooth down final prints.
When choosing which type of 3D printer you want to invest in, you should consider not only the cost of the machine but the cost of material used in printing. One kilogram of PLA (a popular type of FDM printer filament) usually costs around $15-$25. By comparison, 500 grams of photopolymer resin costs around $20-$30. The quality output of the resin printer can be worth the cost difference—it just depends on what you need out of the printer.
Don't forget any maintenance costs. If you plan on resin printing, you'll need a regular supply of gloves, masks, and alcohol for cleaning fresh prints. FDM printers may need a little tweaking here and there, but that's often something handled by an Allen wrench.