It seems that Amazon is no longer stocking PSN points cards and PSN game vouchers. Heading over to the Amazon.com PSN page leads you to a page full of nothing.
The service originally launched in October 2009 and at one point had well over 500 pieces of content. It was even useful as a place to see what was coming to PSN, this is before the PlayStation Blog started “The Drop.”
I reached out to Amazon to see what was up. There have been times when content has been pulled from the store, the 3DS had this happen in July. I was told by an Amazon PR rep that, “We have no announcements regarding this change in selection, however we can confirm that Amazon Digital Video Game Downloads is not currently offering Playstation Network Online Game Codes and Points Cards.”
Old content can still be found on Amazon, but it is listed as “Currently unavailable.” All the codes that you have purchased are still in your Games and Software Library, so don’t panic if you didn’t redeem one.
I will try to get a response from SCEA to see if they have anything to add.