My 17-85 is failing every few shots it gives me an error 99 or error 00. I looked at the canon repair site and it could cost about 150 to repair. My question is it worth repairing the 17-85 or should I look to replace it? If I choose to replace it i can only spend about 600 dollars. The next part of my question if I replace it could I find something decent for that price.