How do you check on the availability of a company name?
Search for registered trademarks at the U.S. Patent and
Trademark Office http://www.uspto.gov If you're worried about
duplicating someone else's company name locally, check locally. The
city or state may have a list of all companies registered as "doing
business" there. You may not use an identical name, but you might
use a similar name, as long as you do not sell similar products or
services. If your concerns are larger than local, then your budget
should include hiring an attorney to help "clear" the name for use
in other places, by checking out numerous state corporate and d/b/a
registries, state trademark registrations, trade journals, domain
names, as well as the federal trademark database mentioned by
another contributor. Start by using an ordinary online search
engine to find out who may already be using a similar name, where
they are, and what they sell.