It is usually more cost-effective to retain an existing customer than to acquire a new one. This is true for all businesses and more particularly for a small business. A small business should try to not just meet, but exceed a customer's expectations from it. When we do something even a little more than what is expected it often delights the customer. When I buy guavas from my fruit vendor, he often quotes a price of 4 for Rs. 10. When I do make the purchase he sometimes throws in a 5th one free. This unexpected extra delights me. Delighting a customer need not even always involve giving more of the product - it could be in faster delivery, customisation, extra service, or even a pleasant word - anything which goes a little (even very little) beyond what the customer expects.
Very often a small business may not be able to compete with its larger competitors in many fronts such as price, brand, reach etc. In such cases the 'little extra' may be its only competitive advantage that can enable it to stand up to its bigger, more resourceful competitors. A 'delighted' customer is very valuable - he keeps coming back .. and spreading the word about his delight.