You'd like to finish your basement so it's more useful, but you don't want to spend a lot of money. You want a floor that's attractive, durable -- and cheap. No matter what flooring you choose, you need to eliminate any water or moisture that can affect it, so start by waterproofing the basement. Then consider your use of the space. If there's a lot of foot traffic from outside, choose flooring that's easy to clean.
Paint is generally your cheapest basement floor option. Use a good quality epoxy, usually two-part paint, and follow the manufacturer's directions exactly, as some epoxies and concrete paints require sealing, etching or other preparation. You can vary the look by blending colors to make the paint look like granite or some other stone.
Concrete stain is another inexpensive option. It is similar to paint, but stain soaks into the concrete to color it and usually is finished with a protective sealer. It is longer-lasting than paint because it soaks into the concrete rather than just coating the surface, but stain will not hide cracks and blemishes in the floor. Most concrete stains are water-based and can be applied with a brush or roller.
Linoleum or Vinyl
Linoleum or vinyl tile are common flooring options. Both are fastened to the concrete with mastic or cement, come in many different colors and patterns, are easy to clean and durable. You can install either tile or linoleum yourself; tiles are easier to lay than big rolls of linoleum. Prices vary widely, but both are more expensive than paint or stain.
Ceramic tile is another good choice, generally more expensive but longer-lasting and more durable. You can cut costs by using larger tiles, up to 16 inches square, and installing them yourself with a tile mastic. Ceramic tile covers small cracks and defects in the concrete, but it must have grout between joints and needs to be sealed against spills or moisture.
Rubber mats make an attractive and softer basement floor, usually comparable in price to vinyl or linoleum. Most have interlocking edges to hold mats together. They are comfortable, durable and waterproof, and you can vary colors in attractive patterns. They're easy to install yourself because they can be cut easily to fit.
Carpet is attractive and affordable. Indoor/outdoor carpet usually is the least expensive option and easiest to install yourself. It's also more resistant to moisture. You can buy this in rolls or in squares with an adhesive backing so you don't have to fuss with mastic or cement. Regular pile carpet is more expensive and most subject to dirt and moisture problems.