I have been a Blackberry user for about 7 months now and I actually just downloaded Blackberry App World onto my phone directly from the browser. I know that accessing the browser will cost money, but will having Blackberry App World on my phone cost any money and will accessing the App World and downloading apps (free) cost any money?
Yes, the App World accesses the same data connection as your Browser. If you get charged for using the browser, you'll get charged for downloading free apps. Tip: Use WiFi when downloading apps.
If you switch off the MOBILE NETWORK and use ONLY WIFI for browsing/downloading/Facebooking/Tweeting bla bla - you will definitely NOT be charged (Data / Money).