Not sure whether it's prohibited to recommend anything (considering that I'm a newbie here) or not. But I've been using a site called MP3caprice com It probably won't have everything your neighbour is looking for, but it's got a decent selection. It's about 12 cents per song/$1.20 per album, and you get an MP3, which you can save, backup, or whatever you like - and if you lose/delete them, you can re-download.
There may be better alternatives out there, but it's probably cheaper than iTunes.