I was at the dealership today for service on my '07 Si sedan and they had one in the showroom. It was $32,000 after the $2500 "market availability" markup, which is too much IMO. Plus, I was surpised that the Mugen got much lower fuel economy than the Si without any real power gains.
I would love to have those wheels on my Si but they're way too expensive right now. They're ridiculously light though.