1 key faulty on Macbook Pro Retina - is a replacement keyboard, battery etc the only fix?

I have a 2013 MacBook Pro Retina which had a cup of tea spilled on it. The machine works perfectly except for the 3 key which is not responding. I've taken it in to an Apple Authorised Repair Centre who said they needed to replace the keyboard, battery etc to fix it at a cost of £600.

Is there any other way to get this single key working for less than £600?

Thanks in advance for your help.