Line of Credit
The only thing you can be sure of in business is that you can never be sure of anything. A line of credit can give you the financial flexibility and muscle, providing additional operating capital, as well as funds to purchase equipment, or cover temporary shortages.
Get pre-approved for cash to spend as you need it. You only pay interest on the amount that you use, and you can pay it off and use it again, so you've always got access to extra money if you need it.