settle this for me: how much is a click?

Nobody can settle it with one number, because it's an auction. You pay roughly what it takes to beat the next advertiser on that search, so a click on something cheap and uncompetitive can be pennies while legal or insurance terms run into tens of dollars. Plug your actual keywords into Keyword Planner and look at the top-of-page bid range. That's your answer, not an industry average.