A couple of months ago I would have advised you to look at the George Wright WPP200C - IMHO a great unit for the price, under $900 as I recall. Unfortunately George passed away recently so you can't get a new one, but they (and the older but still very good WPP100C) are available here and sometimes on craigslist.
You certainly couldn't go wrong with a good pre-loved Audio Research PH-3 or better yet an SE model. They're seriously good units (for the price) and if not your cup of tea you can resell it for what you paid for it. Some folks rave about the Jolida JD 9A- it's said to be another very good tube phono stage in it's price range ($450 or so).
Finally, I would suggest that you take a look at the Soundsmith mono cartridges. They are true dual coil mono units, so you can use the mono cartridge with a normal stereo phono stage. According to Peter "Doing so gives added dimensionality, while not detracting in any way from the advantages that mono reproduction has over stereo. This makes switching between VPI arms to go from mono to stereo a breeze. No changes required at the preamp. Swap arms, and youre done." The last comment is assuming that you are also using a Soundsmith stero cartridge.