Andrew it isn't so much the need to buy the perfect or favorite bottle, nor is it about a minimum spend threshold.  It is about putting a bit of thought into the purchase.  No different than buying any gift.  If you were going to buy someone chocolate you probably would seek out something a little nicer than a Kit Kat so why wouldn't you do the same with wine?

And yes a case of beer or a bottle of spirits is fine if your host is not a wine person.  But again hopefully you skip the Canadian and find something a little more interesting.

Obviously your choices should still be guided by the recipient's preferences - no point in bring a red or lager if they have a strong preferences for white or pale ale.