They are dirt cheap on eBay if you ever get the itch. No DLNA, though, which your current solution supports. So many guests would be left in the cold. But an A

They are dirt cheap on eBay if you ever get the itch. No DLNA, though, which your current solution supports. So many guests would be left in the cold. But an Airport Express plus an RPi serving as a simple DLNA-to-Airplay bridge might be a way to go (Thank you for the great article, by the way!)