Like they always say, if it is possible to make $1 via a certain method then it's possible to make a million.
It's obviously a matter of just trying different stuff which YOU think will work.
CPA offers though aren't as often promoted through SEO as traditional affiliate programs because offers get changed around often, paused, resumed, then paused again, and/or discontinued within a few months.
If you find a CPA offer which has the staying power of say a Clickbank product then I say go for it, and if you're trying a site with offers which often get paused like email submits, you'd want to have multiple offers on the page.