The price range of Spectors, understandably, varies depending on the model. Top of the range are £3k+, entry models change hands for anything between £100-250. The through neck/ set neck versions are more desirable.
The NS2000 is very desirable and under-rated IMO - I had two which I should never have sold during one of my down sizing periods - I don't know why I bother, I just spend the money from the sales on more gear. Think £300-500 depending on condition.