(Reuters) -Sales of previously owned U.S. homes ticked lower in August amid affordability issues for buyers thanks to still-pricey homes on the market and interest rates on mortgages that remain relatively steep despite recent drops in borrowing costs. Home sales slipped 0.2% last month to a seasonally adjusted annual rate of 4.00 million units from an unrevised 4.01 million in July, the National Association of Realtors said on Thursday. Economists polled by Reuters had forecast home resales would slip sl ...