I know a guy who didn't have workman's comp last year. He thought the chances were too slim that someone would ever get an injury on the job. Then... a freak accident occured. A worker got poked in the wrist by hedge trimmers that weren't even running. The guy's tendons were completely severed from his fingers and shot up into his arm. His hand will never be the same again. The owner of the business sure does wish he had workman's compensation insurance.
Don't be stupid. Have good business ethics and do everything right. If you can't afford it, then you are paying too much or charging too little. That's my two cents.