Also, anyone know what these things are worth? I got mine for less than $1k.
It's worth what someone will actually pay, "guessing" is futile and misleading.
That said; here's some examples of what people
actually paid.
6-01 1974 for $1,901.00
6-24 1976 for $1,600.00
7-27 2nd Gen for $1,226.99
7-31 1973 for $1,695.00
It appears that for some reason (right place at the right time, condition, etc.) that
yours was "worth" less than $1000 when you bought it. It would also seem that you could turn a tidy profit on yours if it's in decent shape.
If it's for sale and you want the biggest reach and highest bidder, list it on eBay. Or settle on a sale price and list it here, Craigslist, or whatever.
I personally think that all vintage Sunn tube amp values are hurt by the association with doom, drone, stoner rock etc. The tonal attributes of the 4 output tube Sunns are loud and very hi-fi, not dissimilar to the attributes that influence the appeal of vintage Hiwatts, but I think the general association of "Sunn" with that lower end niche genre vs. the association of Hiwatt with the broad appeal of the affluent and more mainstream classic "British Rock" genre keeps the value of Sunn gear repressed.
Just my opinion, of course.