I have one blog that averages 1,800 UV a day, which earns me anywhere between $8 - $20 a day.
I have 3 other blogs that get about 150 UV a day each, that earns me total around $5 a day.
And I have dozens of other blogs with 1 - 10 UV a day, which all up earns me about $1 a day.
Monthly totals, I average 50,000 UV, 150,000 PV and make between $500 and $900 a month.
In my experience at the very least you should be making at least $1 for every 1,000 page views, as an average you should be making $3 - $4 per 1,000 PV, this is where I'm at, and if you're actually good at it anything above and beyond that.