There’s a big difference between selling a Librem 5 that you have … and selling a Librem 5 that you expect to have at some unknown future time, under conditions (shipment, taxes, warranty, …) that are awkward to arrange at best.
In addition, the OP is attempting to ‘take advantage of’ the price difference between the earlier prices and the current price (never mind about the future price).
If you sell a Librem 5 that you have then a buyer knows exactly the price that a new phone could be purchased directly from Purism, avoiding all of the awkwardness of a private transaction - and apply a discount from the then new phone price to account for the negatives of a private transaction.
I don’t think you need to invoke heresy and blasphemy 
to explain the scepticism of many people who have posted in this topic.
It’s just my opinion but I think that if the OP wants to have a “change of mind” on the sale, when Purism is not offering that, then it should be done at a small loss. Even then, I wouldn’t touch it.