They fit on any keyboard with Cherry MX switches. The spacebar might only work on Cherry boards, I'm not certain, but all of the other caps should be fine on anything else. They're NOT cheap, which makes them fairly unique. I just ordered them, along with some other stuff, from Taobao through obook, and the CounterStrike set was ~$90, not counting shipping from there to me.
Here's a link to the set I ordered, they changed the colors around a bit since the previous run, and they include a Steam key for ~ now.