I went the eBay and Amazon route and spent about $50 for a wired back up camera. Here is the camera I bought
linky that has lasted almost 2 years and several trips thru the car wash. I bought a $20 TFT monitor on eBay and a 15' RCA extension to complete the package. The video quality is not as stellar as the factory set up on my wife's Exlorer but it gets the job done. As KMP44 stated, there is no depth perception with the camera mounted low but I learend where the shadow the tounge casts on the ball to figure out where I need to be.
