Halal certifier Mohamed El-Mouelhy sues anti-halal campaigner Kirralie Smith for defamation, page-129

I think you will find the $13billion is the sale of Halal certified products not Halal certification fees.

Companies that he Halal certification do so so they can export to Muslim countries, with 24% of the world population being Muslim that's a pretty big market to tap into.

In most cases Halal certification costs very little and requires little change to the manufacturing process, for example Sanitarium (owned by 7 day Adventist church) don't use alcohol at all so their Halal certification is a simple inspection was all that was required.

Some manufactures use alcohol based cleaning products and to get Halal certification all they need to do is switch to non alcohol based cleaning products