You might be able to sell the NOS Speedlight crankset at around 75 bucks without chanrings at this time. It's just competing with too many similar looking and aged cranks out there, specially ones from Campagnolo (Veloce, Centaur....etc). It really looks like a very nice, good quality crankset, but it's still a bit too new to attract C&V collectors/bikers with the cash to spend on older components who are usually looking mostly for 50's to early 90's stuff for their rides, so this crankset have not really been on their radars that much......yet.
Let it cook for a few more years and you should get much more money for it.