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If you want advertisers you have to make them money in the long run.
If you can't make sales with a CPA program why would anyone want to pay per click or even per impressions?
The only reason would be if you site was very popular which according to your post, you only receive a few hundred impressions.
I don't mean to be rude but if you start thinking past the point where you make money I think you'll be better off in the long run