This is a Sunn Enforcer, really. One went on ebay for 400 bucks three days ago. There were several of these made, Ted owns two in snakeskin, if I remember correctly.
They aren't worth BIG cash. They may be somewhat rare, but I've personally seen two or three Penetrators in person, and countless Enforcers, so they aren't ~that~ rare. So, I won't give you an exact number, because I have a moral issue with giving valuations based on a picture, and not a multimeter/hands on test. Anywhere between 400-600 bucks, is my guess. They just weren't all that spectacular... Frankly, this may be the only mediocre amp Sunn ever made.