This very nice example came up on Gbase in December 2010 with the dealer asking $4,900. Here's the description:
"Get your Joe Perry on with this 1970 Ampeg Dan Armstrong lucite guitar. Remember Keith playing one of these on Ed Sullivan way back and and you saying "WHAT is that!!! These were all the rage back then and still are to collectors & players like today. They originally came with about 3 pickups that are very easily switchable. Unfortunately this one only comes with one. Fortunately, it's the rock/treble pickup which is THE one that will give you the sound these babies are known for. Serial number A612D, this member of the TrueTone Music Real Deal Collection is a solid 8.75 in condition and just SCREAMS!!!"
A612D now comes back on the market in January 2016 with an asking price of $3,795 (Reverb listing). Seems to be the exact same guitar, case, and single RT pickup. Thumbscrew has gone missing along the way and been replaced by a small washer and machine screw. Seller said: "1969 Ampeg Dan Armstrong Lucite Plexi Guitar W/ OGHS Case. One pick up RT. 100 % original !!! And Original CASE!!!"