There is a type of gutter guard that you can buy known as a mesh gutter screen or mesh gutter guard. These guards are just what they sound like. They are mesh screens that sit on top of your gutters guarding them from debris like leaves, twigs and other plant material that blows around during a storm. These gutter protecting items are easy to install and inexpensive.
The way they install is that one end slides under the shingles at the edge of the roof and the other end snaps into the front gutter lip. The design is such that the screen will not sag when weight accumulates on top and they will not slip off. The only tool that you will need to install it is the gutter cleaning ladder you normally use when cleaning your gutters. The holes in the mesh allow the water to fall into the gutter system while keeping out the unwanted debris. Of course, some dirt and unwanted items will make it through the mesh. When it comes time to clean your gutters, the mesh gutter guards are easy to remove. You just unsnap the front portion from your gutter and you can lift it to clean.
In terms of price, you can purchase versions of this type of gutter guard anywhere from twenty cents per foot to one dollar per foot. It comes in many different colors depending on the color of your grout system.
One down side to this type of gutter guard is the fact that the mesh can get covered up completely. The mesh is actually a material that leaves and debris will stick to readily. If the entire mesh cover gets covered with leaves, there is nowhere for the water to go. In this instance, the gutter guard is more of a problem than a solution.