Star's are good pistols. Not rare or anything so I wouldn't pay more than $250-$300 depending on condition.
Parts and magazines are damn near obsolete especially for the Firestar series. Use factory mags, the only aftermarket ones are cheap crap. They come up on gunbroker every now and then.
I like my M40(Firestar in .40 S&W) a lot, pretty good carry gun aside from the weight. They are all steel so they are extremely heavy.