The cost depends on your state and business activities. Your best bet is to contact independent agents and them them SELL you on one company or another. I am with Safco, and I like them. I have 1,000,000 coverage for under $500 year. General liability and vehicle contents coverage of $2000 for tools and up to $5000 for equipment I carry to install.
Other states can cost three time that for less coverage.
Sticking with the same company you have now might be more beneficial in the long run. After five years I received a good customer (no claims) discount. Ask your existing agent about such programs.