A $2 CPM would be great. These days I'm lucky if I can get a CPM of 12c. Although that's still much better then what I've been able to get with CPA ads.
Statistics:(40K users, 450K page views)
Insurance(banner): 36 clicks, 0 sales
Tires(multiple banners): 82 clicks, 0 sales
Tires(click here type links tied into content): 213 clicks, 0 sales
Leasing: 12 clicks, 0 salesHowever, there are studies that show an increase in overall ROI when using display and paid search together. In this context, CPA ads are beautiful to the advertiser because they know they won't get conversions on them. But people are clicking. So they get free branding impressions without the cost of impressions!
I understand that you've had issues monetizing a site with it but that is far more likely to be an issue with your target audience or your advertising strategy.
If you don't get conversions from your CPA offers I'm guessing your CPC and CPM ads aren't converting well for the advertisers either which as we all know isn't going to last for ever.