Although I dont like BINs I have become more partial to them- since twice I lost stuff that I was trying to get cheaper-- and at the end it went higher than the original BIN..
I've found if you are patiant and careful you can find many items much cheaper than they end up going for with BIN. Usually you have to catch them the day they are listed but I have gotten items 1/2 to 1/4 the selling price of regular acutions several times.
Thing is that tactic is never 100% so it's not very reliable. Still some great deals on vintage and HTF items have come my way with it.