I found this on kijiji yesterday:
"Rare, 1978 100Watt Sunn Beta Lead head. Reverb and 1st channel doesn't work, but I've used it as a single for years with great results. I should say, it makes some funny noises on low volumes, while not at high volumes. Could be a good project, as these are rare, and very sought after. Used by Buzz Osbourne (Melvins), Kurt Cobain (Nirvana), Adam Jones (Tool),and Slash"
He's asking $200, would it be worth fixing it so both channels work? How much would that cost?