which mac or keyboard do you have?
i have some spare keyboards for powerbooks (bronze to new ones) and ibooks (clamshell and new) avail. I could send you a key if you need of i/Powerbooks.
if you live in US, you could ask in the apple retail stores. if they have spare keys, they may be able to help you. I havent changed the keys in just keyboards, only in i/powerbooks.