Is there some sort of iTunes kiosk, a publicly accessible device with iTunes installed where a customer could purchase songs, download them to removable media and then move the songs from the media to whereever they need to have them?
Or maybe you can use a friend's device with iTunes installed?
You can use a friend’s machine. Either create your own Apple ID there or redeem your gift card using your friend’s Apple ID and buy music from their account. After that you can just copy your music to an USB stick or to Dropbox or whatever.
Yes, you need iTunes to buy – but once you have the music, you do not need it anymore. They are just standard audio files that work with any (somewhat current) player.
Is there some sort of iTunes kiosk, a publicly accessible device with iTunes installed where a customer could purchase songs, download them to removable media and then move the songs from the media to whereever they need to have them?
Or maybe you can use a friend's device with iTunes installed?