Maybe you sellers could add in what the "right price" was?
I dont know what its worth, all a guy can really ever do is study the market until your eyes bleed, then throw out a price you feel is within the given market. It really matters not what you have spent or invested, its only worth what someone offers you that you can accept. If your over what the market will bear, no one will ever call.
Then you have the electric drive to consider. I dont believe anyone could know what the electric drive is worth, or if its a detractor. It might help to give details as far as approx hp, the motor specifics, prop used, maximum speed, as well as maximum range. It may also help to give details as to how your charging the batteries, and costs, if any, that that might involve (electric bill, etc..). Its probably a much better modification for something your going to keep long term, than what it would be worth to someone else. My guess is a savvy buyer, even one who might really appreciate the mod, would try to talk it down. Your job is to talk it up as best you can, and be able to back it up with a good sea trial if need be.