Visa's valuation is more than fair considering the quality of the business.Credit card companies like Visa (V 1.02%), Mastercard (MA 0.88%), and American Express (AXP 2.25%) continue to benefit from a transition away from cash toward digital payments. Visa is now the third most-valuable company in the financial sector, with a market value of about $550 billion, behind only Berkshire Hathaway and JPMorgan Chase.Visa has fallen almost 6% during the past two months and is little changed on the year, drasticall ...