My 20 inch Zenith that I bought about 10 years ago lost all of its blue on the screen, so the color is really off. After some research, come to find out it's a chip inside the TV that controls the Red/Green/Blue color signal. Technically it should be an easy fix. I never got mine fixed, so I can't tell you how much it would cost.
I think you have the same problem, so the question is how much it will cost. For me, it was cheaper to go out and buy a brand new TV than to repair something 10 years old. If yours is newer, you might want to get it repaired.