Seems like it took quicksellstore a significant amount of time to sell for 9, so Im not so sure excluding that is a good idea, especially since it is very likely that their purchase would have been even lower.

I cannot find any current buyers on either marketplace or bptf - its hard to verify how long the mentioned buyer has been there on mp. Based on what I see here I think 13 flat is going to be too high here; I would prefer a range or a third sale.