There's a '71 Sunn Solarus head and matching 2x12 cab on my local craigslist. I emailed the guy asking about tubes, caps and general functionality He tells me that it has no footswitch, tubes are good but he didn't say anything about caps, so I assume they are original and could probably use replacement. He said that the tremolo doesn't work until the knob is turned to 4 and that it hums because the ground broke off the plug (but he has a replacement plug he hasn't put on it).
He also says that it has replacement speakers (Eminence Red Coat Governors) and that when he got it all the pots crackled and the volume would cut out if the bass was turned above 4, but those issues have been supposedly been rectified. He says that the issues with the tremolo (which I'm not too concerned about) and the broken ground on the plug already existed then but he didn't have the money to fix everything.
So assuming I like the amp, what should I pay? He doesn't have an asking price, he's taking offers for it as well as a few guitars before he's supposedly leaving the country. In my initial email asking about its general condition I offered $500, he countered by saying that when he'd listed it for sale/trade a few months ago he was offered over $800.
My gut feeling is to not go over $700 (even doing that I'd have to sell either my Deluxe Reverb RI or my Mesa DC-2). Are there any other questions I should ask before trying it out?
Here's the only pic of it I have from his craigslist ad:











