What one needs to understand is that it is an auction and that prices are dictated by market forces. There's a reason insurance related keywords may cost $10 for top spot. It's because even at that cost, it's worth it. Don't think you'll pay five cents for them, even with the best QS ever, because that will never happen. You must follow the market.
I manage many accounts in all kinds of sectors. Yes, some pay dollars per click but many others less than that. It depends on the sector. Occasionally, you do see a click cost much less than an average in that sector, say a fifth to a tenth of the average, yes sometimes even down to ten cents or less. I can show you clicks that cost just one cent in the last year (account average is 40 cents) but I don't expect all my clicks to be that low.