Looking to start a referee business, any idea's ?

[bossref]

BBRef thanks for pointing out that he wasn't looking
to start assigning. My mistake.

More on topic:

A group was mildly successful around 1990 by running leagues for businesses. I think it was called Corporate Sports America.
Lots of businesses want to build esprit de corps and do so
by sponsoring teams in basketball and softball.

There are also "social" leagues that charge an annual membership and fees per event.

You might want to consider renting a gym for ethnic groups or church affiliated organizations.