One thing to bear in mind, particularly for US-based FT'ers is that aerohkg.com charge 2.5% a surcharge for credit card transactions which is permitted in many Asia Pacific countries (as opposed to the US, where merchant rules forbid it).

So if you actually went ahead with an aerohkg.com booking, you'd be informed that the total price is x dollars (usually exactly as shown on the website), and that your "credit card price" is x dollars + 2.5%.

Not sure if Tiglion do this also.

If they don't, the bottom line may work out better.