Accepting credit cards will often double... even triple your current sales. Studies show businesses that accept credit cards can see a huge increase in volume... almost overnight. Accepting credit cards will legitimize your business. Studies show that when you display credit card logos as forms of payment you accept, these logos create a sense of 'trust' in your customers mind, and if they trust you, your customers will buy from you.
A merchant account will significantly improve your cash flow. Accepting cards has a huge positive effect on business cash flow. Even if sales don't increase (and they almost always do) your business will benefit by having the money from the credit card sale instantly delivered to your bank account. No more waiting for check to clear, or sending out time consuming invoices, waiting for payment. With credit cards you get your money from your customers quickly and easily.