I have seen so few CS45's for sale that it's hard for me to judge value, but a search of completed GB auctions reveals a going price of around $500-$575 for very nice 95%ish examples, $750 for LNIB collector-grade guns, and a few examples with significant wear in the high $400 range. This seems consistent with other 45xx-series 3rd-gen models that aren't proverbial needles in the haystack.
I've been cautioned that availability of CS-series mags in general can be spotty, although prices aren't necessarily higher than other S&W factory mags. IOW this is one of those pistols where the number of spare mags should be a prominent negotiating point.
I know that standard 39-series mags and 391x/394x compact mags will work in the CS9, but I'm not sure about other 45xx-series mags in the CS45. OTOH it should be easy to find out because full-size 45xx-series 8rd mags are fairly plentiful, and unlike the 40xx-series and 9mm 3rd-gen guns, all of the 45xx-series pistols are single-stack. (The 40xx-series mag situation is notably bungled because S&W built single-stack and double-stack compact pistols with the same model number!