The best businesses to have are ones that allow the customer to pay cash, or by debit etc. The way this is an advantage is that you have no waiting time for the funds to arrive, nor do you have the situation where a client might not pay on time - the goods are delivered, the customer pays, simple as that.
The costs of setting up are not too bad, either, as you can now get a receipt printer at reasonable cost, whether it be one that uses heat sensitive paper, or what they call an 'impact printer', where the initial cost is slightly lower, but the running costs are very slightly more. Couple a unit like this up to a scanner that can pull the prices off by using the bar code, and you can even have a single employee serving masses of customers.