Oct 8 (Reuters) - AvidXchange Holdings Inc on Friday raised the top end of its proposed price range for a U.S. initial public offering, with the business payments firm now looking to raise up to $550 million at a valuation of about $4.8 billion. (Reporting by Sohini Podder in Bengaluru; Editing by Anil D’Silva) Our Standards: The Thomson Reuters Trust Principles.