Just burn the songs to CD, in regular music format.
That way you will never have to purchase the same song twice, or 3 or 4 times. That is what iTunes really wants you to do, buy the same song over and over again for each ipod you have.
Better yet, buy your music from
Amazon.com, no DRM control, it is yours. No need to buy 3-4 times over many years.
Even better thought, don't use iTunes, use a different podcatcher software, then copy to your MP3 player. Everytime I see a post that it is not in iTunes I laugh. I always get the podcast right away when they are released. It takes a long time for iTunes to update, if it does it correctly at all.
It is your music, podcast, equipment. Take control of it, don't let iTunes control you stuff, it will loose it at sometime, and you will have to buy it all again if don't back it up correctly.