Booking an air ticket

I went to the Sri Lanka Airline website to book my air ticket to Colombo. I found this website to be well designed and easy to use  - much better than Jetstar or Singapore Airlines. I got a good price. I asked my travel agent if they are able to match this price - but they cannot. I went to Expedia.com but could not find a comparable price (but the price was a good benchmark). It seemed that the best price can be obtained by booking directly with the airline.