JuicyAds is an open marketplace and how you price your ads is completely up to you.
There are many variables to consider when pricing a zone such as: Country Origin of Traffic, Volume of Traffic, and Clicks and Impressions.
Many Publishers prefer to set specific prices manually so they are guaranteed a specific price for their space. Most Publishers use our Auto-Pricing option to have the price set daily based on the amount of clicks to your ads.
Remember, every website is different so there is no "formula" to set prices, some websites can demand higher prices and others are not so lucky. It's all about supply and demand.