Wonder why travel sites show the same prices?

If you haven't booked your summer vacation yet, here's a time saver. Don't go to a dozen sites looking for the best fares. A consumer advocay group says theprices are often the same because most of the sites are owned by two companies, Expedia and Booking Holding (formerly Priceline). John Matarese has other suggestions for getting the best deal on hotels and airfares.