Flights from HK to Saigon & BKK/Phuket

We have some friends coming to stay with us in HK before they head off to Saigon and then to Phuket.


They have booked a flight from the US to HK and then leaving Bangkok to go back to the US. From HK they want to fly to Saigon and then from Saigon to Phuket and then to BKK. The fares they have found in the US are not at all cheap or even reasonable. We suggested that they book their asia flights originating in HK (i.e. on a HK website) as we were under the impression it would be cheaper to do it that way.


We have seen ads in the newspaper here that claim very cheap fares to many asian cities but when we look at their website we can not find any fares anywhere near that cheap. The cheapest we could find HK to Saigon was between $350-$700 US without taxes which seems pretty steep.


Any ideas on the best way to go about booking good fares? We are recent arrivals in HK and haven't had the need to book any flights ourselves yet. Thanks.