I have an Aubrey that sounds exactly like yours. I think I paid around $450 for it in a GB penny auction a few years back. It should be worth more than that, but there is just zero collector interest in them. It is basically valued as a shooter and nothing more. If your friend doesn't believe that, let him advertise it for what he thinks its worth and learn the hard way.

"Life is too short to hunt with an ugly gun".