I have had a very strange experience with this.
1 million general business liability policy. Remember, if you trailer you need to move your truck/tow vehicle to a business policy, almost exactly the same amount of money though, no big deal. Also, this is not property, so if someone steals it, you're boned.
1st year of business (did maybe 15k revenue): $700
2nd year of business, first company drops business liability, guy finds $1100, only did about 20k that year (got married)
3rd year, came up for renewal, new guy had bought the agency went in adn said "find me something better, my carpenter friend who does 80k a year pays less than this"
He did, $200 (he's the man, he's gotten a lot more business from me because of that)
This year it will go up because we're going to do a lot more, big time expansion of the business (at least we're going to try)
But that's pretty **** reasonable
Many places won't write policies on businesses not in operation for 3 years or so much revenue. So, get it early and it appears the price goes down after a while. (makes sense, more history)