Sometimes these bids will vary dramatically. This can result in unsatisfactory work that will cost you more in the long run. Make sure that the bids include quality materials that are guaranteed by the supplier or manufacturer. Competitive bids are free of charge and will ensure you pay a competitive price for your project. Ask to see their current license.
Most states require that contractors be licensed.
You should also verify licensing with your Local State License Board. Ask for proof of insurance. Take the information and call the insurance company to verify that it is currently up to date. Also, if they have other employees, ask if they have workman's compensation. This is required by law.