New Brl assemblies average about $209.95 from Bushmaster. $350.00 plus from Colt.

What is a used in excellent condition brl assembly worth? 75% of new price? 50% of new price?

I believe that one must be specific as to what constitutes a barrel assembly when offering something for sale or seeking to buy one.  I have seen varying descriptions.  Handguard,gas tube and delta ring/snap ring etc. Included or not?
Anyway the point is to list what parts are included so there is no confusion.  As a ball park figure,yes a used part in excellent condition and used very little should bring 50 to 75 percent of new value.  As always the value is what a willing buyer will pay.