I started using adwords in 2005 and I was paying 30 pence a click, I was right at the top 24/7 for that, my monthly bill was around £35
I don't do it now, it's too expensive for the price shoppers you get, last time I did it briefly a few years ago it was £3.90 ish per click
I think you'd be paying at least £700 a month now to be at the top 24/7