I didn't realize, 'till I saw this thread and went to look, that they were discontinued. I would imagine that Ruger lost a lot of business when Kel-Tec introduced their pistol-caliber carbines.
Quite true. Basically, Kel-Tec snagged the lower end of the price range, while Beretta and Olympic Arms continue to take the upper end. There's not much of a "middle range" when it comes to pistol caliber carbines.
I'm sure the Rugers are a better gun but you're having to pay more for a gun that only uses Ruger mags when you could turn around and buy a Kel-tec that can be had in configurations that use any one of several popular pistol magazines (Glock, S&W, Beretta, and Sig).
In all honesty, while the Ruger's do have a heftier construction, they really don't have any advantages over the Kel-Tec's, aside from the fact that you could use one as a club more easily.
Surprisingly, though, if you look on Gunbroker.com, you can run into a PC9 for about the low to mid 300's, which isn't that much more than the Kel Tec Sub-2000. Also, Ruger P-series magazines are fairly plentiful, and can give you that 15 shot capacity.
I just really didn't like the PC-series' gritty trigger. I could probably have done a bit with some metal polishing on the steel contact points, but at that stage, it simply wasn't worth it, and I ended up selling the PC9 to a friend, who *did* like that awful trigger.