The times of expensive ringtones from the internet are over now that iTunes software can be used to design jingles for iPhones. Just enter the desired audio segment of 20 to 30 seconds into options for the song title and transform the clip to an AAC format.
The file ending .m4a must be changed to .m4r and then the ringtone will appear in the corresponding section of iTunes and can be transferred to the iPhone via cable connection. As an alternative to iTunes, this can also be done with the free programme iringer.