WV and I have both done business with an ebayer who exaggerated the size and strength of the hi zoot Spectra, Kevlar, and Vectran cordage he sold. By a factor of 2, I think. Perfectly nice fellow, but he didn't know what he was selling.
If it is Spectra, and related to parachutes it is likely NOS because Allied Chemical got out of the business long long ago. It may be rather fluffy, in which case it will snag and not wear well. 50c foot is expensive. See next paragraph.
You can buy Amsteel Blue, of similar fiber for $.25 /foot +.05 /ft shipping on 100feet, and know that it is 1500lb bs strong. Either mail order from a vendor here, or copy the prices from Redden Marine and go to a marine store eg West Marine that price matches sells Samson 7/64 Amsteel Blue.