It would help to see the whole keyboard to be sure of the model. This one has function keys both left and top?
I owned one of these after Northgate stopped selling keyboards. Personally, I don't think they're as good as the Northgates, partly because of the change to simplified Alps, and the keycaps are inferior. But there should still be a market.
I don't know the current value, but you might get $100, maybe more. I'd probably put it up on eBay and let the market tell me what it's worth.