I know it's a crappy answer, but its value is purely dependent on what the next owner wants to pay for it. I've seen prices on vintage fridges range from $50 all the way to $1000 and up, it just depends on what value they put on the features yours has.
I bought my 1949 GE fridge for $100, replaced the door seal, replaced the insulation (putting a hole in the evaporator in the process and lost most of my freon), repaired the evaporator and had it recharged by an HVAC friend. So to me, that fridge is worth well over the $100+ that I've put into it, especially since I can fit 4 ball locks in there. To my wife, all she sees is rusty yellowing paint and the fact that it's a beast to move and she would probably pay someone to haul it away without a second thought.
If a vintage fridge has original drawers and shelves and everything is in good working order with a nice paint job and no rust, it will be on the higher end to someone looking for a nice vintage fridge. Since you've put holes in yours, there's no shelving and the evaporator is hanging by the wires, that crowd will likely offer you $50 or less if they offer anything at all.
To a homebrewer who wants a vintage look kegerator to use as is without putting much work into it and if it comes with the tank, lines and faucets, I'd say upwards of $400 is reasonable if you help them move it to it's new home.
Put it in a sales thread and see what offers you get.
