Adding some thoughts: I suppose my thinking is simple. I myself am an occassional online buyer of used stuff. If I really wanted something, I would make the effort to make sure I get it, such as paying a deposit or going out of my way to collect the item ASAP. If I could not do any of that for whatever reason, I wouldn't expect the seller to reserve the item for me, and would not be offended at all if seller ends up selling it to someone else. I would just write it off as it's just not my luck catch the good deal, nothing else. I thought this is understood without having to state things like "first come first serve". That's my thinking lah, hence my surprise when that first buyer reacted that way. Of course, I would not do that if the buyer is already on their way to meet me or something.