Buying a physical copy of a book is a little different, as it does offer some additional benefit (in terms of portability, different medium, whatever). However, let's say that your argument is that some people will like the author and "buy" a copy of the music they already have, even though that copy offers zero additional benefit to the consumer.

That's a donation, not a purchase.

Buying a physical copy of music in the form of a CD confers addition benefits over a downloaded MP3 as well, one of which is the higher quality of uncompressed 16 bit audio (or better, if SACD or DVD-Audio versions are available).

You can get flac rips at private music trackers like waffles. The library is comparable to if not better than itunes. There are some 24 bit rips out there but not very many.