My dealer voluntarily offered me one for 30% off list the other day with taxes thrown in. I wasn't even looking for one. I declined. The stock seat is excellent.
The manufacturers are making it harder for the aftermarket guys. The stock Busa pipe is so good, for instance, that it's virtually impossible to improve on it by more than a couple of HP.
Lots of guys out there with PCIIs and Microns who are still getting under 160 RWHP.
Even Suzuki's own optional Busa Gel Seat is, by concensus on this board, not nearly as good as the stock seat.
Is a Corbin worth the premium it was worth 5 years ago? Not on the Busa.