I agree about the enduring popularity of Dutch bikes, and your arithmetic is also correct.
However, a buyer could realistically get a discount on a new Juicy which would come with a full warranty - your bike is a year old so has no warranty.
The likes of Kudos have similar spec step through bikes listed at £865.
Dave who owns Kudos can speak for himself, but I suspect he would take £750 for cash - again giving the buyer a new bike with a warranty.
Ebikes are like cars, they depreciate off a cliff from new.
From a marketing perspective, a buyer will want a newish bike to work when he/she buys it.
What they don't want to do is mess around ordering expensive parts to get it going, particularly as a potential buyer may not be experienced with ebikes.
If the battery is completely dead, a buyer is bound to fear the bike may not work with a new battery.
Buying an ebike - particularly a secondhand one - without establishing the motor works is a risk.
You mention cheaper batteries being available.
One approach would be to buy one of those, fit it, and say nothing about it.
You may then achieve your £400 asking price.
