Running Mac OS X 10.5.8 because it is still perfect for me.
In late 2012 the Buy button on the iTunes store suddenly stopped working.This meant I was not able to send money to Apple for music downloads.
Contacted Apple Support who told me the only solution is to upgrade OS or get new laptop.
This week I saw online that others have had the same experience and in a forum I discovered that the solution is actually:
1. To ignore the buy button next to the song you want.
2. Drag the track you want to your PURCHASED list.
3. The track will appear in the Purchased list with a buy button next to it. This button works.
To make you feel better you can download my music from bandcamp via: