I saw the cables were on sale at my Target too, but since the Nook HD+ that I bought to use as an Android tablet seems to be exclusively an ebook reader

I haven't been able to convince myself it's worth getting an HDMI cable.
I'll have to go back and see again; if they go below $10, I might find it worth throwing the money away on it, on the chance I install some app that is NOT a book reader app on it!