We have plenty of sites at http://BuySellAds.com that earn a $5-$10 CPM from direct ad sales. In any tech related niche, $5-$10 is pretty darn good. It also depends how you define CPM. You won't find any single ad unit itself commanding a $5-$10 CPM, but in aggregate, based on what is ACTUALLY sold, they hit that $5-$10 CPM range. Networks love to throw CPM figures around, but what really matters is what is sold at a given CPM rate and for how many impressions. We like to look at CPM from an overall site earnings perspective. I.e. Your site has 1mm pageviews per month - what are we making for you off of those 1mm impressions in total (which includes what is unsold and naturally reduces the effective CPM for the site)?
Fill rate (i.e. sold vs. unsold) is something to think about. Let's say you can command a $15 CPM from some advertisers -- would you rather have a 30% fill rate at the $15 CPM or a 90% fill rate at the $7.50 cpm. If your site has 1mm pageviews per month then you're looking at $45,000 vs $75,000. I'd be perfectly happy with a $7.50 CPM in this scenario.
$10 CPM is at the bottom of the rate card for publishers like newspaper websites, etc. When we were doing advertising for Stormpulse we were making $5-12 CPM off direct sales and $2-3 CPM off ad networks. We knew the direct sales prices were actually selling ourselves short.
It depends a lot on the area. I run a moderate-traffic finance-related site that gets about $20 CPM via AdSense. (Before the financial crisis put an end to the glut of mortgage-related ads, it used to be more like $40.)
On the other hand, I run a music-related site that gets something like $0.25 CPM.
As a data point, I run the most popular blog in a technical niche and on a total basis, run about $5-6 in display advertising (job ads come to more). E-mail, on the other hand, is a lot better.
The only ads I run in e-mail are text (since text converts better with my geeky audience and they hate images as it is). I'm not sure what mainstream e-mail people do but images seem to be a lot more common there. If someone's paying $275 CPM to Thrillist for an ad - http://www.businessinsider.com/what-a-275-cpm-ad-looks-like-... - then I hope they're getting the full value on that ;-)
Fill rate (i.e. sold vs. unsold) is something to think about. Let's say you can command a $15 CPM from some advertisers -- would you rather have a 30% fill rate at the $15 CPM or a 90% fill rate at the $7.50 cpm. If your site has 1mm pageviews per month then you're looking at $45,000 vs $75,000. I'd be perfectly happy with a $7.50 CPM in this scenario.