I'm not as familiar w/Sky's as much as Sols, other than noticing that a Sky in like condition as a Sol is generally $1500 to $2000 more. Carbon Flash was a special color run and from what I have read on here there may have only been around 500 in that color? (if someone has a specific breakdown please post). But I wouldn't let the seller know that.
Back when I was trying to decide between a Sol and a Sky I did look at a Carbon Flash, and thought it was beautiful. However…I also thought it was the type of color that had to be spotless all the time because the metallic could also look like a fine layer of dust on the black paint.
If I had to put a price on it, I'd say 12 to 14, but I think I'm on the high side compared to NADA or KBB values. But then when it comes to values, private Kappa* sellers tend to ignore those sources. But just so you know, prices for Sols & Skys continue to be all over the map. I've seen low mileage cars w/great prices, and I've seen high mileage cars w/ridiculous prices. Kappa prices will continue to drop in the future, how low is anyone's guess, and as far as collectibility goes, I place both the Sky and Sol in the cult class. I think of a cult car as a car that has a small group of fanatic followers/enthusiasts, but its still isn't accepted by mainstream collectors.
Also, if it has a manual that's better yet since auto's outsold manuals 3 to one on Sols, and I'm assuming it may be the same w/Skys. With the demise of auto transmission in general, there may be a day that manual cars are worth more than autos, collector car wise.
*Kappa is the platform name that the Sol & Skys shared.