ESI don't exist anymore. IET Labs have taken up all their old stuff - and they are the type who don't give a straight price but ask you to request a quote. Get involved with salesmen, etc. Which is basically a F.U. in this day and age.
Now if those binding posts are anything like my ESI RV622A then they will be as loose as a whores chuff. I don't know exactly what the specification was instead of 4mm banana but I think it was some kind of old Bell Labs telephone plug standard?
They are of course gold plated tellurium copper and all that.
If you really want the retro thing then find me some 4mm gold plated tellurium copper with teflon gaskets from, say, Pomona and I will swap them with my old ESI stuff?