Hi guys, I have a musician friend who has a 1977 100 watt Marshall JMP for sale with no mods. It has a few tears but it overall in excellent condition. He told me it was made for the Japanese market as there is a voltage switch I think he said on the front of the amp. Anyways, I played it last night last set with my band and really thought it sounded great. I don't want to lowball him, but also don't want to pay too high a price. What do you think would be a reasonable offer? Thanks!