If you delete the app from your device and then re-install the app and do an import, the prices on your device can get jumbled. This is because the website still thinks its database is still in sync with the database on the device. (The sync between the two databases allows you to update prices on the device and have the website updated correctly, and visa versa.)
To let the website's database know that the sync between the website and device database is gone and needs to start from scratch, there is a new button on the website called "App Deleted From Device". Once the app has been deleted from the device, click the "App Deleted From Device" button which will restart the sync between the website database and the device database. Then you can import your prices from the website to your device with no problems.
Thanks to a user who alerted me for the need for this button.