While there really are no average business liability insurance costs for both small and large businesses, we can consider some sample scenarios. 1  A sole proprietor might pay $500 per year for general liability insurance, but a small consulting firm is likely to pay over $3,000 per year. A sole proprietor who hems garments out of a home office has limited liability concerns, but a landscaper may pay upwards of $15,000 annually due to increased risk.