Append track price to individual track

Hey folks I have been banging my head against a wall here and I'm hoping someone can help me with a solution. When tagging songs from Amazon, iTunes, etc that offer individual MP3 tracks ... I am looking for a way to tag each file with the associated cost of that track.

For instance:
Track #1 Foo is $0.99
Track #2 Bar is $1.29

I have tried making a user defined field (ie AMAZON_TRACK_PRICE) and having the value appended when tagging. However, it is just appending the last amount to all the tracks. Sadly, that is not always the case as I have seen in iTunes where tracks from the same album can be different prices as in the example above.

So, what I am hoping can be accomplished is a user defined field similar to the DISC# field that is used in the lower left of the tagging window .....

I hope that someone has a way to make this work or possibly a better solution ... I look forward to any pearls of wisdom that you can impart.....

Never mind folks ... I got it to work the way I wanted.