CREATE TABLE table_70472 ("Date" TEXT, "Tournament" TEXT, "Winning score" TEXT, "Margin of victory" TEXT, "Runner ( s ) -up" TEXT)

What was the winning score of the Buy.com Siouxland Open?
SELECT "Winning score" FROM table_70472 WHERE "Tournament" = 'buy.com siouxland open'
SELECT "Winning score" FROM "table_70472" WHERE "Tournament" = 'buy.com siouxland open'