We have had an older Woods 21' chest freezer for oh must be 25 years now .. it was 20 years old when we got it. Compared to our 2 energy star 15' freezers it probably is cheaper to run based on our bills. It certainly is a much better built unit and will do well for many years to come.
If it were a fridge, I would have no problems getting an older fridge for the shop. We used to have a round top Kelvinator that Dad built into a nook under the stairs in our house back home in Timmins. I always liked the look of the 50's era fridges and freezers. So I have a soft spot for them.
However, as David said they are worth a specific amount to collectors and probably even less to those who might want to use it. Check you local Penny Saver or Kijiji, CL or whatever and see what used freezers are bringing. Factor in the age. I will bet that the right price is somewhere between $50.00 and $100.00 but I would be leaning closer to the lower number unless it is in really great shape.