What is the best deal for an inexpensive DIY backsplash?

I have always painted my backsplashes. I find that if the floor is patterned and the countertop is patterned, the kitchen ends up looking too racy.

Along that line, you can also sponge more than one color on the wall...whatever goes with the rest of the room...like Marion said, not too busy. Sponging covers up all sorts of imperfections on the wall, too.

I used a tile patterned wall paper that was printable. When it was dry I painted it silver. I love it but you can paint it any color you like. It was trimmed out with wood flooring trim.

Plexiglass, have a home Depot, Lowe's, etc. Cut to fit. Screw in walls and you can get little flower, Daisy's that fit on screw heads to look nice. Easy to clean looks very nice nice, about 1/8 - 1/4 inch thickness. Easy to replace if ever needed. Cost effective and looks nice.