Which is on sale right now through Audio Advisor, along with a whole bunch of other Cambridge stuff. You didn't specify if you needed MC capability, but the 640p does both MM and MC.
I really don't think you can nail down one "best" phono stage, as there are so many offerings now, all of which are very good. You can also look in the used market for extra value. For example, I had a Creek OBH-8 for quite a while, that I picked up for $100 with the upgraded external power supply. I liked it alot, but it is moving magnet only, and I decided to try MC cartridges.
Lots of folks who can do a bit of soldering really like the Hagaman Bugle. If you don't solder than it comes assembled direct from Hagarman. It is battery powered by default, which makes it extra quiet, or you can pair it with their external power supply, which I think is currently only available in kit form. MM only, however, in its "stock" form, though I've read of guys modifying the design so it will accommodate MC.
Other options to look into that I've seen folks mention they were happy with:
Parasound - Zphono MM/MC Phono Stage
NAD - PP-2 -MM/MC
Music Hall - PA-1.2 - MM/MC
And, of course, the options mentioned above.
Again, check the used market on sites like Audiogon. You can likely pick up a deal there on a good phono stage.