The Institute for Supply Management鈥檚 March manufacturing index slowed and costs rose to the highest since August, ISM said Monday.ISM鈥檚 factory index fell to 50.9, from 52.3 in February. Readings above 50 indicate expansion.The index measures U.S. manufacturing activity. Economists had predicted the index would decline to 51.4, Bloomberg reported.鈥淎 positive for March is the customers鈥 inventories index . . . which is a possible indication that manufacturers鈥 inventories are nearing satisfactory levels,鈥 said Norbert Ore, chairman of ISM鈥檚 manufacturing survey committee.鈥淥n the negative side, prices appear to be surging for certain commodities in the face of slower growth,鈥 he said in a statement.The prices-paid index jumped 6.5 points to a 65.5 reading, the highest since August.