God bless Canada and this small firm called Replacement Laptop Keys - that I found by just googling around desperate to find a solution.
Ten days ago my 'X' key on my MacbookPro just went off it's plastic case. I was silly enough to mess with glues and stuff (yes I know silly me). The only thing I managed was to break the plastic base and the rubber cup on the bottom. I felt like an idiot. I started to search for alternatives - even replace my macbook pro keyboard - something that resolved to a potential cost of 400 euros (OMG!).
After some googling, I found Replacement Laptop Keys. They were selling a replacement key, the exact plastic base needed and the rubber cup (this one I thought that I wouldn't find). They have a smart and simple wizard to make you choose the appropriate key and components depending on your laptop (they cover a lot of models). After a week (they ship international as well) a small envelope came with the key and the 2 small parts. I cleaned my broken 'X' slot, and installed the new one. Its like new! I am very happy.
So if by any chance you do have broken keys on your laptop - check them out - you will save lots of money and your keyboard will be up and running in a couple of minutes!