Pricing is supposedly $30 for a pack of 3 cymbals, or $15 each. They are from Mad Catz, technically, but they will be licensed as official first-party add-ons. As mentioned earlier, the cymbals can be played interchangably with the same colored pad, but they do appear to be independent inputs. Rock Band can distinguish which one you’re hitting during fills — hit a tom and you hear a drum, hit a cymbal and you hear a cymbal.
It disturbs me a little that the cymbals are add-ons — so learning to rely on the physical motion of hitting a cymbal will be unnatural on a “stock” Rock Band drumset.
My current strategy is to try out the Guitar Hero World Tour drums, which include cymbals, to see if I enjoy playing that way or not. I have to buy the full GHWT kit because I definitely want the new guitar, and at that point it’s almost as cost effective to buy the full Guitar Hero World Tour band kit for $190.
Similarly, the new Rock Band 2 Drums are available as a standalone kit for $90, but by the time you factor in the $60 price of the game, you’re already at $150 — and fairly close to the price of the Rock Band 2 Special Edition which includes game, new drums, new guitar, and microphone for $190.