How much to charge for advertising? PR1, 32,000+ unique views a month

It started as a hobby, but grew quick, so I need to get something out of it in order to keep it up. It is a music site and I'm trying to get at least enough money to cover the costs of maintaining it.

PR1
32,0000+ unique page views a month
Over 18,000 visits a month
Over 15,500 unique visitors a month

Also, all signs point to steady increases in all of those figures. How much should I charge? I'm thinking of doing either 4 or 6 125 x 125 sidebar banners.

Thanks.

 

If the adds are fixed, no rotating banners, $50-60/monthly can be a good price to start.

 

IT would entirely depend on the keywords you are running your site on.

Well, it would be worth not less than $25 to have 15,000 visitors to see the Advertisement Atleast

Thanks.