I plan on making several marine electronic equipment purchases over
the next few months for my new boat in Florida.  I am amazed at the
huge markup on these electronics.  How do I become a marine equipment
retailer or reseller so that I can purchase them at wholesale?  I do
plan on selling some of this equipment to other boating friends with a
slight markup.  I do not wish to do anything illegal I am just looking
to save some money.

Start a company (differs by state on how to do that
http://sbdcnet.utsa.edu/sbdc.htm) and apply for dealer status with a
few wholesalers like

http://www.cwrelectronics.com/