I have the kit lens, but the rainbow flare issue doesn't allow me to take pictures at night very easily and i would like to so i have been looking for a replacement...i was thinking about the 17-40 but its sooooo expensive and i am still in school...it looks like the 20-35 sells pretty cheap on ebay and might be good..what do you think? is this lens worth it to replace the kit or should i wait for the 17-40?

