This fretless bass neck apparently came up for sale in 2007 and was being offered at $99.99. Seems like a bargain for anything approaching a decent Dan Armstrong neck, although the neck also has an "R" after the serial number, indicating a factory second. Here's the seller's description:
FRETLESS BASS NECK
Brazilian Rosewood - Beautiful & Rare
I found this rare Dan Armstrong fretless bass neck in the 1990s at a New York City guitar show. The neck is used but in very good condition; the finish is smooth, the truss-rod & all of the side position-markers are intact. Sorry, I don't have the bolts, tuning machines, screws or truss-rod cover.
Approximate Dimensions (inches):
> Full Length: 32 in.
> Length of Rosewood Fingerboard: 23 in.
> Width (at nut): 1 5/8 in.
I have some additional photos available upon request."