Our local Dollar Tree is currently carrying bone shaped laser pointers in their pet section.  The package contains a laser pointer and two sets of batteries for a buck - you can't beat that!  I believe Dollar Trees carry the same stock at most all of their locations so it's worth taking a look at your local store.  Laser pointers and non-toxic bubbles (also at the dollar store) are fantastic for tiring Ruckus out when I'm too beat to take him for a long walk.