This one came up for auction in April 2013, offered for sale at $2,195 but the auction ended without a buyer. Seems to be missing its OEM knobs, but those are easily sourced and will slip right on.
"Beautiful Lucite guitar in great condition! Tasked by Ampeg with improving their ‘Grammer’ guitars, the late Dan Armstrong produced a number of innovative designs using non-traditional materials. Perhaps the best remembered are the Plexiglass models; this is a fairly rare fretless version of his bass. It’s in good original condition and plays well. Seems to be in late 60's with the serial reading D2229A. Comes with OHSC and sounds great"
D2229A is back on the market in November 2015 with an asking price of $2,300 (sold for $1,650 on November 3, 2016). Still in very nice original condition and now with correct knobs. Only blemish we can find is a missing screw in the pickguard. Case seems to be an authentic Ess & Ess case, with the very early blue interior and the early-style handle. Interesting to find it paired with a 1971 bass...
“It's Lucite, It's clear, it's an original 3rd year issue, it's 44 years old. 4 digit serial number. Very cool, look just like Bill Wyman!!”
"1971 Ampeg Dan Armstrong Lucite Fretless Bass. Please examine these photos carefully. Purchasing this instrument acknowledges condition and authenticity. No Buyer's Remorse. We won't have it. IF you are not familiar with this instrument, please save both of our time. The Original case included. NO RETURNS due to age of instrument."