A1273D came up for sale on Reverb in August 2015 with an asking price of $3,400. Seems to be a nice example, but the 1970 serial number does not match up with the later bridge plate and saddle, which are clearly from the end of the run. Love the split-shaft tuners on this one, which were a short-lived feature and consistent with serial numbers in this range. Pickup definitely looks to be original, likely a CB or RT from this time period.
"This Ampeg Dan Armstrong guitar was made in the USA in 1970. It shows wear but no damage. It plays great and sounds great. The pickup on this one does not have the normal 2 letter code on it but appears original - but I cannot determine which pickup it is. It is pro-setup and needs nothing. It comes with the case in the picture which is not original."
Same guitar being posted on Ebay in September 2015, but with a new set of pics...$3,495.