So, a relatively quick item I came up with for treasure, a modification of the pearl of power. It works as a standard pearl of power, using a full round action to recall a spell you already cast. Alternatively, if you can Channel Energy, you can do so as a full round action and add Xd6 to your channel, where X is the level of the spell the Prayer Bead works for.
I think the value would be about 1.5 the corresponding pearl of power.
Any thoughts?