Here's a thought. They have steps to making paper mache horns in this blog. Hearing Shofar: DIY Shofarot for Kids
Granted these are for blowing, but the shape is right. All you'd have to do is leave out the noisemaker, paint them how you like, and then attach them to an ear bonnet with some velcro strips. You could cut out the ear part of the ear bonnet if you wanted his normal ears to show. Like nicole said, they are cheap. They also come in black.