It's a Calypso first stage (don't know if its a III, IV, or J). I don't know them well enough to speak to their value. The seconds are the 1085 (used on Conshelf, Aquarius, Calypso). Those are simple, bulletproof, and chrome. Those look like the chrome is in good shape, but hard to tell from one picture. The seconds are super easy to DIY maintain, and service parts are readily available. Off the little info given, I personally would try to negotiate.
My advice is always worth what you paid for it though!
Respectfully
James