I got a $16 click yesterday - I about fell out of my chair. I think it was a newbie AdWords advertiser who blew his entire budget with 5 clicks.
I am just getting started with adsense as ive only been in program now about 3 months , i usually avg around .12-.25 cents per click and biggest one ive had so far was $2.54. cant wait to get one of those $4 clicks congrats on yours
That all depends upon the Niche hes working on and this is very much possible cause competition in paid advertisement might be too high in his niche and advertisers may be paying too much.