Polo Ralph Lauren’s same-store sales are up, and its net income increased 6% in the quarter ended Dec. 26. An impressive showing, but Steven M. Rogé, a portfolio manager of R.W. Rogé & Co., says the stock is too expensive now. At 79, it trades at about 17 times trailing 12-month earnings. Rogé would buy it if it fell to 40 – it slumped to 31.94 last March – or 12 times earnings.