The insurance rates would vary greatly from state to state and from insurance company to insurance company. It would also depend on if you are working from a home office or from a commercial space, and whether or not you own or rent; another factor would be any inventory you have. Just call a few of your local insurance agents and get some estimates. They can usually get those pretty quick for you.

I have an online business that I operate from my home. I pay approximately $45 for 3 months of business/liability insurance. When I had a brick and mortar retail store, I paid about double that amount.

Hope this helps.
Tina