I think you got it partially right, if the bid exceeds the purchase price then the seller has no obligation to sell it for less, so it could be $300K or more, right?
In regards to not posting on ARV site, good point. This is an interesting van but the market very tiny, eBay could give him greatest exposure, the question is, is it a right exposure.
I asked the owner on the Sprinter Van forum why is he selling, no answer yet. He was very proud of it when he introduced it to the Sprinter forum in 2016. I recall him stating that if he is not going to like it he will do something else, couldn’t find this post but found this post about his objective for the Womp.
https://sprinter-source.com/forum/showpost.php?p=447565&postcount=262 and yes since he still struggles with Amps.
Looking at his pictures I was a little surprised that his van wasn’t even washed before taking pictures.
Wishing him best, but I think it is a difficult sale.