Probably the single redecorating or home improvement item that makes the biggest impact is paint. A new, bold color or a new, sedate one will make all the difference in the world to your home. Your patio is no exception. Don't live with a drab, boring patio because you can't afford to buy new furniture or redo the floor. Just paint.
Paint anything that's paintable, and that includes some floors, wood, plastic or metal furniture, plant pots and other decorations. Half walls and lattice can be painted, too. Choose your color and get a few paint brushes and some rags and you're on your way to a brand new patio!
Then if you really feel the need to do more, you can still decorate it frugally by finding furniture and other items second hand. A little elbow grease and maybe some paint? It's the frugal way!
Sometimes just a good cleaning spree can do wonders for a patio, too, but patio furniture might be a challenge to clean. If it simply won't clean up... paint it!