It is a common practice that eBay sellers drops prices of BuyItNow items in order to move their inventory. For sellers managing large inventory, they use software to automatically adjust prices bases latest sales data. Since the goal is to move inventory while keeping maximum profit, seller don't usually tell the buyer there is pending price drop.
Some buyers manually tracks price changes of the items they are monitoring, but this is a very manual process.
Good news for eBay buyers, latest version of JoyBidder has implemented price alert feature. You can enable price alert on selected items and get alerts you when price changes.