It's a Branch Manager Grapple (I'm a rep/salesperson for Top Notch Equipment/Branch Manager Attachments on the side). What it's worth always depends on the buyer, but I would ballpark around $1500
A new grapple is $2399 (without the 2% forum discount I offer) and it has these advantages:
Wider opening, that one should be around 46-47" whereas the new version is ~53-54".
Updated knuckle to prevent the holes from wallowing out
Updated dogs on the bottom and dogs added on the front.
Pushing spikes on the tip of the hanger for pushing trees over.
Reinforced tines on the grapple, although that era had less issues with bending the tines.