Raising lab animals is big business BAR HARBOR, Maine (AP) -- When it comes to the price of mice, you pay extra for defects. A mouse with arthritis runs close to $200; two pairs of epileptic mice can cost 10 times that. You want three blind mice? That'll run you about $250. And for your own custom mouse, with the genetic modification of your choosing, expect to pay as much as $100,000.