Here's a really nice example of a 1970 Dan Armstrong bass, AND it includes the original warranty card and truss rod tool. Just came on the market in December 2015 for $1,650, seems priced to move.
1970 Dan Armstrong Plexi Bass 1 Owner
"Bought new on Jan 8, 1971 from Amp City in Denver CO. Still here...the bass not the store. Played for 10 years then tucked away in a closet until recently. One pick up model. Comes with Warranty card - filled out but never sent in-two spare wooden bridge pieces-instruction manual/brochure and truss wrench. Just restrung with string that are pictured XL 170s with fretboard cleaned and conditioned. Original case."
"Very minimal fretwear. Everything is in excellent condition regardless of age. Very clean piece. Been used but not abused."
Back on the market in February 2016 through dealer Chicago Music Exchange with an asking price of $2,095.
Neck: Maple neck with a medium-round profile, 1 5/8” wide nut, rosewood fretboard, 7.25” radius, and dot inlays (serial number dates to 1970)
Pickups/Hardware: Grover tuners, one rail pickup (Rated at 8.4kOhms), two-way switch, volume and tone controls (all original, 1969 pot codes)
Cosmetic Condition: The body shows average play wear but the bass has definitely been well cared for and is in great shape for its age. The brown pickup cover has a few small chips above the rail but it is purely cosmetic and does not affect the functionality of the pickup. The neck has some normal lacquer wear but overall it is nice and smooth with only a few small blemishes that do not affect the playability one bit. The headstock is also looking great with only a few light dings around the edges. This Dan Armstrong bass is looking fantastic!
Playability: The strings are nice and low, play great, and ring out clearly across the board.
Weight: 9lbs 12oz
Case: Original hardshell with warranty card and manual