The CV 50mn f/1.5 is a fantastic lens. I use it as much as the Ziess 50mm f/2 Planar. And I use these two lenses more than any others! For the money, the CV is hard to argue against; a few vendors still have a few new ones in stock.
I own both the Jupiter 3 and 8. They don't see much use because my copies do not focus well on the M9. One of these days I'll figure out how to calibrate them. From my limited use, I like what I've seen. The bokeh from the 8 can be quite harsh (not a criticism), and the rendering from the 3 can be quite dreamlike. Once calibrated, I'm sure I'll be using them.
You may also want to consider the CV 35mm f/2.5. It really is quite good, good price, and a few vendors have them in stock. Like the CV 1.5 this lens has been discontinued. The general consensus is that the 35mm has low contrast. But thus is great for bw conversions, or if you're shooting in high contrast situations (mid day, the beach, etc).