There are many hacks to help you rotate the banners. In order really get a CPM network your going to need probably atleast 500k impressions to get invited in.

But usual prices can be anywhere from 2-5 CPM and much higher depending on your niche. For example travel can be 10-25 CPM

I personally have no idea what on earth CPM means. Care to explain it a bit ?

Costs Per mille. The ammount you'll get for 1000 banner views.

Ah, right. Like with google adsense?

Sort of yes, although google's adsense only uses a click system I thought.

Alright. 1 or 2 years ago they used a CPM system, I'm sure of it. Not sure whether they still do though.

I got arround 150.000 hits a day (1000 unique visitors). Can you give an indication what I can earn on a CPM system?

The old amount used to be 0,50 euro per 1000 hits. Not sure whether this is still valid though.

So it would be per day:
15.000 / 1000 = 15
15 x 0,50 = 7,50€ a day?

Google does have a CPM area but that only occurs when someone targets just your site.

And there really isn't a "rule" for CPM rates it just depends on supply and demand. If you use a CPM network and are only on the ROS ads then it will be low, like $2 and lower. But if your ads are more specific and depending on the niche it can be much higher.