$200 for a not even slightly used SB-600 - should I bite?

go for it! since you have the d7000, you'll be able to use it off camera. It's not as powerful as the 910, but it's less than half the price. The menus can be a pain in the beginning, but you just have to learn how to cycle through them.

I'd happily pick up a 600 to go along with my 600 & 800.