Your logic(and business practices) are wrong. You had PERSONAL insurance, no company is going to cover items that are used for business purposes. No matter what you think, the company you had for your PERSONAL renters insurance would have denied the claim as well.
The fact that it is "IT'S NOT EVEN THAT MUCH MONEY" does not matter. It is the fact that you did not have the right coverage. Hopefully in 22 years in business you learned a bit more in how to run a business, and were not doing other things that could come back and "bite you".
Hopefully you have marked the electronic equipment with your identification, and have the Serial Numbers. This way if the police recover the items they can get them back to you.