Prefer new but would consider a good used one.....let me know what you have!
Edit: Found one - thanks!!!!
I had that gauge in my old Mini wagon and I loved it. Nice and compact and great use of space.
But my goodness these gauges have become extremely pricey these days! Seven wants $290!!!
Here's a brand new one for sale at less than half that, $142. (And might even be cheaper when VAT is excluded for export sale)
https://www.merlinmotorsport.co.uk/p/smiths-classic-dual-gauge-with-degree-f-temp-range-gd1301-64078-cb-dual
Because of the fragile capillary tube for the water temperature, I would not consider getting a used one. Way too likely the thin metal tubing will have fatigued from going from the original sale coiled up packaging, then uncoiled for installation use, and back to coiled up for re-packaging for used resale.
MiniSpares has them for £104 brandy new.....but as it turns out, the person I was after one for got one from someone else, so he's good now.