Priceline (PCLN) took a high-volume hit this week along with most other leading stocks. But the stock still trades well above its 10-week moving average. It's made itself a market leader. It gets stiff competition in the online travel business from Expedia (EXPE), Travelocity and Orbitz (OWW). It got a boost in its online airline reservations two years ago when it waived fees averaging around $7 a ticket. The competition followed suit this year,