Having owned both the CS9 and CS45, I'd actually place them at a par, value-wise, or even place the CS9 at a higher price. I've stayed away from the CS40 because I think a heavier pistol handles that round better (personal opinion, I know there's plenty of lightweight 40s out there).
I currently own two CS9s, one stainless, the other black. The stainless has a Big Dog grip, and night sights - I'd value it at $550 if I were going to sell it.
The black one is basically NIB, and if I were going to put it up for sale, I'd place the price at $500. That's what I'd be willing to pay, myself. These are great little pistols, and the CS9, IMHO, is the best of the bunch...