Do you still have your original phone? If you put the music files on that phone and you still have it you should be able to transfer the files over. You bought the music, you own it, you shouldnt have to pay any third party. If you transfered you files via smart switch it should have transferred them. The transfer, however, may not have kept the contact assignments. If you still have the old phone, and it still works, try using smart switch to transfer the music files. Try to assign a sound to a contact and see if your custom sounds are actually in the list.
Also, you may have to redownload the music from the site you made the purchases, so that the DRM goes with it. If you purchased and downloaded from the iTunes store, for instance, you have to go to your account and redownload the song, no extra payment necessary.
