Either of Dave's choices for new are sound. You'd be very happy with the Music Hall or the Pro-ject and they come with the cartridge set up from the factory. This is a big thing as cartridge alignment is critical and not so easy to do at home, especially for someone who doesn't do it very often. The Music Hall has phono preamp built in so your money may be going towards something you don't need. If your amplifier/receiver has phono inputs already, then you spending $$ for something you don't need.
Marco's idea has merit but buying a 40 year old vibration measuring device can be a hit or miss gambit. We are talking about a device that has close tolerance bearings in the arm and the platter that have seen many years of service. Also, the Dual is a rim-drive 'table that would undoubtedly need idler rubber replacement by someone who knows how to do that sort of thing. Are replacement parts available, I wonder.
I'm really enjoying a new Rega P10 that came as an early Christmas present. Traded in the old VPI Aries that weighed about 75lbs total. The P10 weighs all of 11lbs and simply blows away the old 'table. Something to be said for modern technology!
Whichever way you go Corbet, it would be interesting to hear of your impressions between the two mediums. I know which one I think will sound better than the other.
. I have had the setup for three years!