How Do I Open My Own Online Brokerage Firm?

i know alot about the brokerage industry, but i'd like to know who i can go to in order to support and build an online trading platform for stock and bond transactions over the internet.
i've seen a few sites that offer $5.00 stock trades and i'm sure they must be using an interface set up through another host company.
but who is that host company?
it's got to be a company that does the clearing, margining, and cashiering i believe.
the host company would be responsible for the major issues like insurance, backoffice, etc
the few online brokers out there today like Schwab, E*trade and TD Ameritrade are all independent and spent millions of dollars building their platform and have backoffices as well.
but is there a 'plug n' play' solution for a small broker/dealer operation available??

and as trade prices go down, what is going to keep the business from becoming a 'loss leader'?
margin rates?
options trades?
mutual fund fee kickbacks?
advertising on every confirmation ticket/email

First youll need a few licenses beofre you worry about the software

Well ... you say you know a lot about the brokerage industry, but the rest of your post indicates that you don't.
for information about becoming a broker, go to www.nasd.com (it's a big site, you will have to poke around a bit).
yes, there are 'plug and play' solutions for small bd's, but the providers either charge hefty fees, or keep most of the commissions generated. OK if you are an asset manager, and make your money from management fees.
why do you think you can compete with Schwab, TD etc?