well, many edge 2 owners were offered $6K trade in value, to upgrade to an edgefx.
I'm sure there were many (like myself) who thought that was way to low. As the original owner of an edge 2 I've taken extremely good care of for about 9 years now, and continue to get like new results from, it would be foolish to sell it for $6K.
That said, I know they have sold for less, because we live in interesting times, and businesses are closing up every day. I guess I'm saying $6K would be good in my opinion.
The Envision was over $8K new I believe, so I don't think half that would be unreasonable, in good working condition.