Sound advice, and all you can really do.
Asking 80% or higher is not being greedy, it is still a loss on what you paid, but it is probably not going to happen unless somebody wants the item so badly and cannot source it. That is chance that you can take.
I recently paid 80% for a pair of eyepieces which are still available at various outlets, FLO included, but I knew the Vendor very well and his promise that they were less than six months old and pristine, I accepted. When they arrived you would not have been able to distinguish them had they come direct from FLO or RVO or anyone else, and so I had saved 20% and had effectively brand new eyepieces.
You have to 'suck it and see'.