$500K is a horribly large requirement for a license bond. I have only heard of such requirements for contractors doing high volume of business or
money transmitter license bonds. I would start by double checking the amount required, as there are very few start-ups that would qualify for such a large bond.
I am hoping that you misheard whoever told you we need 4 times the net worth of the bond amount, as it is not necessarily true. We represent bonding companies that have a large variety of underwriting guidelines. Some do not have specific guidelines on net worth amount, others might require 3 times the bond amount. It varies greatly and can not be stated quite as black or white as you were told.
After you find out the amount, you can
apply online for a contractor's license bond for a free quote.