Isn't it possible to get the bell symbol in the iTunes Store?
No.
This is how its done in the Store:
Choose iTunes > Preferences, click General, and then make sure Ringtones is selected.
Make sure you’re connected to the Internet.
Select the song you want to use, and then choose Store > Create Ringtone.
In the editing window that appears, choose the part of the song you want to use as the ringtone.
If a song is not eligible, you will see the message: "This song cannot be made into a ringtone."
You can use up to 30 seconds of the song.
When you’re ready, click Buy.
IMPORTANT: After you click Buy, you can change the ringtone’s name and other information, but you can’t select a different portion of the song.