"I could get an cheap cherry keyboard and then just replace the whole space key on the deck one with it."
Damn you, now I just noticed how my thumbs partially polished my spacebar as well!!!
Dumb question: Why don't you just ask Deck to send you another spacebar?
(couple of them while you are there, so you don't have to worry for a while)
Another idea would be to polish the whole spacebar... Make it even.