I agree it certainly doesn't look complete and needing the cobbled up 1x tacked to the legs to stiffen it up makes me also think the legs aren't original.
I blew up the image in the browser but by the time could focus on the joint area of the forefront leg behind the vice the image was so blurry couldn't really tell anything useful.
If it were within a handy drive I'd be sorely tempted to make an offer altho agree it needs some adjustment probably to compensate for the legs to make it usable as a bench.
I agree that realistically, the provenance and quality of the top/vices _should_ make it worth that or near it; finding the right buyer in present condition may be a trick...the really nice thing about these benches if wanting it to actually use is you can reflatten the top; it was normal expected maintenance to do so periodically. If one wants it as a museum piece instead, then the patina and all is the value, not the functional ability.