Setting ad prices
 

Okay, I'm baffled. If I want to charge $1 for 3days, $2 for 7days, $3 for 15days, etc. how do I do it?

You can't. That's one of the shortfalls of the program at the moment - you can only charge someone for posting a day which can run for whatever period the advertiser selects.

I've already said in another thread that the ability to charge advertisers by period is a really important feature.