平價機票......

There are few kinds of cheap air tickets

1. Cheap tickets offered by expensive airlines, booking done thro' travel agencies or directly on web/phone. Like BA CX or SG, they have promotions for HKG->LDN or other major europe cities almost every year Jan to March .. The only thing you have to worry about is to make a booking early. Most of the times these tickets let you stay as long as 30 days but both departure and return flight is FIXED and any changes (even just the next flight out) means chaning the ticket and an admin fee will be charged. (quite usually over 1k HKD)

2. Cheap tickets offered by moderate airlines, booking thro' travel agencies. I'd say this is the most risky one because you don't deal with the airline directly and therefore there are chances that you can be cheated by the travel agencies, in the worst case.

3. Tickets offered by value airlines. In terms of money it's perfectly safe. Fare/Tax/surcharges are usually explained in detail before booking. Same as 1, most tickets are not open and you have to fly according to the booking dates..or else pay for an admin charge(that sometimes even higher than the ticket itself..LOL)

Usually these cheap tickets posted on the newspaper didn't include tax or any surcharge... So when you come to book a ticket, they will tell you a price more expensive then those you saw as they will include the tax and surcharge...
Of course, with cheap tickets, there would be more restrictions as well like no change of date or cancellation allowed etc... However, I don't think you will be reqested to pay extra before you can board the flight at the airport...
As I have said, that some of these cheap tickets will have more restrictions and aldo would not include tax or any surcharge... You can call them and ask for a quote first for the price include tax and surchange and also the condition of the ticket...
Then maybe you can go and have a look at big travel agency and airlines booking website, then you can compare them... Usually when all the surchange, tax and hiden cost are added, the price would be similar to big travel agency and internet or even more expensive...

如果是直接打去航空公司訂的話，就不用怕。航空公司會先收所有費用，到機塲不用加錢，除非燃油附加費。

通常你訂了機票，航空公司會e-mail或傳真班次、時間等資料給你。必定成行，除非這間航空公司倒閉。

最好打多幾間航空公司問一問。

平價機票一般問題不大。

主要風險：

1. 保險問題
2. 是否可準時起飛