This topic caught my eye, because I know sellers who do what the OP describes, but my strategy is normally to do the opposite of what the OP wants to do!
I am trying to eke out a limited war chest, so, if an item is offered for less than I am prepared to pay, I don't expect to buy it even cheaper! Items offered up to 20% below my maximum are my top sniping targets. Then of course there is the option of asking a seller to add one or two recent unsold items to the one I have just sniped.
My experience is that I often see items fail to sell at reasonable prices, but, after sellers relist at even lower prices, they sell well above the original listed price.