Audio Advisor has wall-mountable $800/pair JM Lab/Focal surround speakers on sale for $189/pair here.
Otherwise, for wall- or ceiling-mount rear surrounds, I'd go with Mirage Omnisat satellites or NanoSats. They have built-in wall-mounts and are omnidirectional, which is definitely preferred for surround.
Otherwise, for wall- or ceiling-mount rear surrounds, I'd go with Mirage Omnisat satellites or NanoSats. They have built-in wall-mounts and are omnidirectional, which is definitely preferred for surround.