I have one that I bought in 1981. It was officially used, but it dates to 1981 so it may have been a demo. It has needed a little attention here and there over time, but not very much, considering how long I have had it. I think it's rated at 125 watts or so, but I never know what that means relative to sound pressure. It is loud enough for everything I have ever needed it to do. I wouldn't count on it for an outdoor gig, for example, but for a bar gig, it's powerful enough. The only controls I use much are the volume knob and eq.
I would describe the sound that comes out as more like an Acoustic 370 than a 360 or 320. It can be a little grindy or raspy. If you like a bit of grind, it can certainly do that and do it well with bass. It can be clean at higher frequencies. I don't like the way it sounds with a guitar, but it isn't intended to be a guitar amp. I does work reasonably well with vocals and keys as long as you don't overdrive it. Then it doesn't sound so good.
I wouldn't sell mine for less than $200, just as a point of reference. I don't think it's worth any more than that, but no less, either. It isn't too hard to move if it has castors. As far as I know, the factory installed castors. It's heavy, but its shape makes it easier to move than if the cabinet was deeper or shorter. Mine is more or less permanently at a practice space, and I don't move it. At this point, I don't gig with it and probably wouldn't. Not because it isn't capable, but because I have other amps that I prefer for gigs - namely other Acoustic amps.
Whether it's a good amp for you or not will depend a bit on what you intend to do with it. For $75, it's pretty hard to go wrong if it works.
I wish I still had it. 
Sounded good with bass or keys, though back then I didn't appreciate it as much as I might now. But yeah, I'd hit a working 126 for $75.
