Got a $13 click a few days back in the health niche.
The CPC depends on how good the traffic really is that you are sending to the advertiser.
If the traffic is organic and coming from Google, then you will get better CPC whereas, if you are getting traffic from untrusted sources, then you will get lower CPC but that will increase if your traffic converts. This is all to avoid the Click Frauds. Just try to rank better for the terms that you are targeting and you will definitely see a nice jump in your adsense earnings as well.