Welcome to the forums. The problem you are having is the same one everyone else who upgraded is having right now. Blackberry has go put out a fix. They are aware of the glitch and will release a fix really soon. You can still download free apps with no problem.
There was a lot of chatter among other Blackberry forum users about this problem. Some claim they were able to fix the problem by going into My World in the App World and logging into their PayPal account in order to reconsile their purchases. The fix did not work for me or for a bunch of others. So, short of moving to Europe, we have to wait for the fix.
Stop the presses. I found a fix. On the Tour, and probably any other global Blackberry that uses a sim card. Turn off your phone. Remove the back cover and take out the battery. Looking at the device, below the battery slot on the bottom left is a small sim card that is black and red with white writing and a Verizon logo on it. The sim card can be released by sliding it towards the top of the device. Use your fingernail to get it started. Take the sim card out and keep it stored some place for future use. You do not need it unless you plan to travel overseas any time soon. Replace the battery and restart your Tour. That should fix your problem with App World; it did for me. I am hoping RIM fixes this problem soon.
I know you have the Storm and it is a global device. This might be a problem for Storm users, too. This might be the fix for Storm users who are having similar App World problems.
Ok, I have found a permanent fix for the problem of app prices showing up in Euros instead of dollars. Pulling the sim card will work if you leave it out, but when you put the sim card back in, Euros show up again. To permanently fix the problem do the following:
1. Open Blackberry App World
2. Go to Top Paid Apps
3. Select any one of the apps
4. Click to Purchase. We are not really going to purchase, just cancel the transaction at the last minute.
5. You will be prompted to log into your PayPal account.
6. Once you log into your PayPal account, you will receive a notice that the default currency will change to dollars instead of Euros. Click OK.
7. Now, IMPORTANT....Click on Cancel to cancel the current transaction (unless you really want to buy whatever you clicked on)
8. Go back out and viola...dollars instead of Euros.
This fix works and will change the error where Euros show instead of dollars.