For sale, K1000. Asking SOLD. Free shipping to CONUS. Serial number is #4503. I can't vouch for this myself, but a friend listened and told me they sound warmer/richer than his K1000 with a high serial number.
I bought these from a guy in Denmark, and they did not come with the standard AKG adapter for using a speaker amp. I made one myself from Kimber Cable, wonder solder and a good XLR (got all components from Michael Percy). The guy included another adapter, though-- a 1/4" phono plug so you can use these with a standard single-ended headphone amp output.
A number of people asked for details so I posted more close-up pictures.
Regarding condition: I am not the first owner and these are a fairly early serial number so they are probably 15 years old or so. They do show wear consistent with that age-- some scuffing and wear marks. The elastic on the headband has lost most of its spring, but that doesn't seem to matter for the fit (I have found these headphones always support themselves on the head via the temple pads). I can't find anything wrong with the grills--they are in very good condition. The temple pads have lost most of their spring, and they are probably in need of replacement-- but I dealt with that by putting some foam rubber strips on my head where the pads touch, for a much more comfortable fit.