I have a 2012 3 speed in white. Though I appreciate its virtues, the quality and durability of the finish isn't one of its strongest points. Does the raw lacquer finish attract a premium due to better durability I wonder? The white at least is easy to touch-up, it must be a pain to treat any marks or scratches with the lacquer finish. If it's any help, I bought my M3R with Shimano hub dynamo towards the end of lockdown for £510-00 and considered it a relative bargain in the rareified world of Bromptonland. How prices compare today I don't know, but that might help.
Finding the right buyer in your area who wants what you've got might be a bigger factor in what they might pay than model, though yours might be considered a few upgrades behind current models now.