Hi studio500
The price you mentioned is the fixed charged plan for heavy traffic users.
Basically you just pay as you use with the points you can buy in advance.
The transfer rate is 22.5MB = 1 point and 500 points cost $ 6.25.
For more information about the pay-as-you-go plan, please see the page:
http://www.wpbooster.net/price/
You can estimate how much it would be with the Points Simulator on that page.
Thanks!
