Gah, just posted this in Commuting, but my suggestion:
Rear - Viewpoint Flashpoint ($15 @ Performance Bikes)
Front - Coleman MAX 2AA Cree Flashlight ($25 @ Walmart) + Twofish Lockblock ($7.50 @ fenix-store.com)
Being able to adequately "see the road" for <$50 is a tall order. That Coleman is about the best you'll do for that pricepoint. Hope that helps!