Not an app, but saving a search will do that for you.
do the search.
on the left hand side, you will see a minimum and maximum $, so you can set the price range you want to look at, with your maximum price.
then save the search, and you will get emails when items match your settings.
it isn't exactly what you want if you only want items on your watch list, but it should be a help.
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Buttercup: You mock my pain! Man in Black: Life is pain, Highness. Anyone who says differently is selling something.
