Usually the off colors are the result of either water that is still in between the digitizer and LCD or residue on the LCD screen itself left behind when the water dried. The other thing could be that the LCD driver is blown. Some are mounted directly to a circuit that is part of the LCD, others are part of the main board on the phone or on a "daughter board". Chances are that if you by a new LCD and the driver chip is blown, you're going to get the same result. Your best bet is to file an insurance claim on the phone if you have one and have it replaced.
The only reason you would want to buy a replacement LCD is if yours cracked, when it's wet a number of factors come into play like the LCD itself may not be the culprit but rather a circuit is to blame.