Yes, most shops that work on 206s will offer something for a trade-in value. You won't get much for them though as most of the animal, super stock, limited, SB open, etc classes are few and far between and we all have dozens of used shortblocks and bare blocks sitting around already. I saw another shop selling used sealed short blocks for $75 and bare blocks and sidecovers for $50 on Facebook last week, so figure something less than that for trade value.
We typically offer $50 for a usable shortblock on trade (which basically covers the labor to assemble your parts on the new shortblock.)
Give us a call during business hours if we can be of any help.