Here is an angie's List article on bonding, insurance, and licensing that should answer your question -
As for your question - I would advise you second-think what you stated - "Chavez Roofing ... have a great deal on cost of new roof".. I bet you could find some terrific cost quotes if you took a few hundred dollars cash down to your local building supply store or grocery store where day laborers hang around - I would pretty much guarantee you could get several to guarantee you the best roofing job in the world for a couple hundred dollars - they will probably promise toi show up first thing tomorrow. Does that promise sound like a great deal ?
You should be checking out recommendations and ratings and redferrals for roofers FIRST - short list some reputable contractors, THEN define your scope of work IN WRITING, THEN ask for bidders to come talk about your job and then, after any modifications to your scope of work based on their recommendations, ask the ones you feel confident with (get 3 typically for a reroofing size job) to bid on your job.
No offer is a "good" offer till the contractor has looked at the job or at least has a perfectly defined scope of work to bid to, and no offer sight unseen is a "bid" - it is just a come-on until you have an actual signed contract in hand.