I'm in a similar position; I had an engine built up over ten years ago and it still sitting on a roll-around stand. It was going to go in the panel van, but I sold that. It's built to the Mileage Motor spec—stroker crank and high reciprocating mass—plus aluminum case, Type iV cooler and a filter hanging off the oil pump.
I've got a build sheet that says $4500. But if I install it I know it's going to be noisy and stinky. Ever since I got crosswise on the black ice last winter, I'm leery of open differentials. The Lexus rear drive unit I got for a conversion has an open differential. I may finish the motor mounts and axle pucks and then sell that on.
Acura MDX and some Honda model SUV are coming to market with a similar part in 2017, with twin motors and an software differential (like Arcimoto). While I'm waiting for one of those to wreck, there's plenty to think about with DC-DC inverters, heated seats and all that in the mean time.
I showed it to the business lead for Arcimoto on Saturday, and he kind of freaked out that I would sell it. I told him if I had a job I wouldn't have too. I don't have to work for Arcimoto, I want to work for the company that make body kits for the SRK. The VW motor and a set of Sears Rader VW wheels I've had since the 60s is worth half an SRK, but I can never get what it is worth when i sell
anything.
$3K for a Powerwall is top dollar. It's really not much more than a Tesla battery pack, some control circuits and an expensive plug.