My LBS has the Kool Stop salmon pads (for alu rims) for about $7 a pair, or something like that, but the pads designed for carbon rims are $50 to $75 a pair. I haven't done any homework about the situation, because this really hasn't been on my radar. But if that's not an anomaly, then it's something I would consider before deciding what kind of braking surface I'd want on new wheels, unless the expensive pads last a lot longer.