In my short time working in retail, and having grown up in it, discontinued items were always discounted, often significantly.
The only reason this might not happen is if the item in question is in high demand and has some kid of mystique or legacy value that increases with time and the retailer knows this, right from the time of discontinuation. I can hardly think of any products that ever did that....perhaps an NAD 3020 (like why would you drop the price after it sold over a million units for 10 years? They weren't even replacing it).....something like that.
Otherwise when a product is being discontinued, it's usually because it's getting replaced by something better and hence the older version has been discounted at wholesale, and should be discounted at retail as well.
If you really want it and the retailer won't drop the price, it falls into the simple laws of supply and demand. There ain't much you can do.