This guitar came up for auction in March 2014 and sold for $1,875. Although there aren't a ton of pictures, this looks to be like a really nice example of a DA, and comes with its original case as well as the very desirable Sustain Treble (ST) pickup. We do note that the brazilian rosewood fingerboard has some interesting figure to it, which is unusual as most of these are just plain chocolate brown from one end to the other. Here's some commentary from the seller:
"Selling a 1970 Dan Armstrong Plexi Electric Guitar. It was kept in the original case for years so it is in good condition and sounds great too."
"Yes the serial number is A2260D and i have just uploaded some additional pictures of the guitar. As you can see in the picture, the 2-letter code stamped in the PU says ST. It only came with one pickup when I bought it so no other pickup is included. Also no extra saddles. No cracks on the pickguard and all the knobs are working perfectly."