This seems too easy to be possible. Do CPM networks not allow this? It seems easy to build a site, put up CPM ads for which you're paid $1.50 CPM and then buy traffic (it would have to be NON pop-up, non redirect, decent traffic) at $1.00 CPM and keep the spread. Has anyone done this?
Theorycally yes but in the actual world it doesn't work this way. The CPM ads that provide by adsense is is based on country such as they only pay $1.5 for US traffic. While for non US traffic they pay $0.9. Some more,buying traffic will get your adsense account banned coz adsense will notice there is unusual sudden traffic rise,so they will check it.