I have acquired an old 3/4" Weaver J 2.5 scope with a Litschert "Varmint Master" multiplier (5/6X) and have no use for it. Is it worth anything?

If the optics are reasonably clear, there is definitely collector value.

Stroebel valued the scopes between $100-$200 in 2008, saying examples with early exposed adjustments were worth an extra $30. The Litschert multiplier could be worth at least $50-$100 as well.