First, collusion can mean illegal or secret cooperation. I was intending the latter. No shenanigans intended here.
But please discuss with me your reasoning why you think secret collaboration would be wrong.
My intended purpose would be to hold the seller accountable for a lack of planning, at best (or punishing a possible liar and profiteer, at worst) and help restore balance to the car market by seeing "value" be greatly diminished by just taking it off the lot.
Further, buying this vehicle from a near-random private party of CaB and dealing with a lien is far less convenient than paying MSRP at a dealer where they do all the paperwork and you just drive off. Plus the buyer is going to have to pay the CaB fee. I'm hoping for a sub-MSRP transaction here, even without any collusion.
And let's not pretend that secret collusion doesn't happen on the selling side on BaT and CaB. Several instances of friend accounts and shadow accounts bidding on behalf of sellers. The sites catch it sometimes, but not all the time.