How do I measure trailer value?

How do I value these two trailers? They are with one of the two boats I am considering, and to be honest I am just going to dump them (I am wet slipping, etc. - never moving them anywhere).

When I think of actual value I think - If I put them on Ebay at no reserve, what would I get?

1984 Load Rite Double Axle. In 1999 replaced wheel bearings and suspension on trailer and put in extra leaf spring. New wheels and bearings in this period as well. In 2004 transom tie down straps and lights on trailer replaced. Mechanical winch appears to be.

Super basic single axle under a v20 right now. Guy wants $500 for the trailer, but that seems way high?

Thanks