Hi Keith, Uv filters will balance the extreme contrast between light in a shot or scene. If you watch car programs or have seen car photography the sky can look very blue with good contast/exposure with exposure on the car being spot on as well. This is due to the filters compensting it. Me personally I save the expense and use photoshop to do the work for me and adjust an area if there's extreme light ranges in an image. Hope that helps a bit.
Try www.warehouseexpress.com for cheap filters.

Filters also protect your front lens glass.