Well before you commit to that you need to talk to your rep and tell them you won't buy anything until you can do a smaller test of $5k first. The brand advertisers are gone and networks are desperate, even if they know you're bluffing they'll probably let you do it anyways.
The second thing you need to do is some competitive intellegence, start scraping google for results with your keywords. Then write some code to visit each site you scraped and save any sites that containt that networks banner ad code, for example if it was adwords/adsense then you'd look for something like this:
And then save all the websites that contain that code and start seeing how long the advertisers are sticking around. If it's more than 2 weeks you've got yourself a good placement. You can also try scraping the top 1 million websites for quantcast and alexa:Code:google_ad_client =
Quantcast top 1 million
Alexa top 1 million
+ Rep
Awesome post. Now I only need to know how to intergrate that in a tool.