Is the courier business a good business to get into in Phoneix, AZ?

I've been thinking of applying with Ontrac in the Phoenix,AZ area for an independent contractor position. I wanted to know what the typical starting wages are, and what amount companies are willing to reimburse you for gas per gallon. I've heard of companies willing to pay you for gas, and some aren't. Also what is the number of hours you have to put in per workday? Will I always need a GPS to find my way around the city, and are routes random? Right not I make 400 dollars a week with a company in an unrealted field, and I have worked their for three years. I've grown tired of it, and was hoping that I could find a courier job that will allow me to make the same amount, or more. I've head this business can be lucrative for some drivers, but for others it's not. Can your reccommend some companies that are good to work for from experience? What kind of qualifications must one have to be a courier driver?