Last time I spoke with someone at Wolff they said they had no plans to make recoil springs for the CS series. The reason had something to do with them being single, flat-wound springs (instead of dual/captive units).
The recoil spring for the CS9 is unique to that model in S&W parts. It's painted red.
The S&W factory parts list shows:
Part # 263210000 $3.26 RECOIL SPRING
You'd have to call and figure out which way the sales tax (if any) and shipping would add to the total cost depending where you order it.
I finally ordered a dozen recoil springs each for my CS9 & CS45 because I was spending more on shipping than I was for individual springs whenever I ordered them.
Then again, I shoot them a fair amount from time to time, too.