Frankenfe, I'll take the front one =) How much? I am assuming that what you are referring to is that it is a regular smooth silver Comstar. The Comstars I have on the bike are the "reverse" Comstars, basically the spokes are stamped, and Honda decided instead of making them all the same, they'd flip the stamped spokes around. I'd really like to keep the reverse Comstars on as 95% of the cafe CX's have regular Comstars and I want to be different... But I haven't found any reverse's in 18" front. I have a connection for an 18" rear, but it's going to cost me $100 just for shipping from Europe and if I can get a regular CX from Bob's in PHX I think it will be much more cost effective. I'll just have to paint them different than everyone else.
I think the Honda CM400 automatic came with an 18" front reverse Comstar? Not all years but I think I saw one once upon a time?
Most of the Cafe CX's I see have reverse Comstars but with the Harley-esque 16" rear, and 19" front. I have 18" front and rear on my CX 500. BTW a single rotor can be made to work fairly well with a CX 650 dual piston caliper and bracket it's a bolt up. That and a braided S/S line and a drilled rotor would do pretty good work. The CX master cylinder is too large for a single piston and that gives the brake a "wooden" feel so the extra piston from the 650 caliper will improve the ratio of M/C to caliper piston area and give a better feel at the lever. Two cents.
Cheers, 50gary