Vietnam beat Malaysia 2-0 at Hanoi's My Dinh Stadium on August 19, securing a 4-0 aggregate win and a place in the final against Thailand.
The first leg will kick off at 8 pm on August 22 at Rajamangala National Stadium in Bangkok, with the return leg at My Dinh Stadium on August 26.
Demand for flights to Thailand rose sharply after Vietnam reached the final, leaving fans with limited options as they sought to arrive in Bangkok before kick-off.
A survey by Dantri/DtiNews showed wide differences in return fares from Hanoi to Bangkok on August 22. Vietjet Air fares reached nearly VND 20 million, including taxes and fees, while Vietnam Airlines tickets were around VND 12.6 million and Thai Airways about VND 5.4 million.
Fares from Ho Chi Minh City were generally lower. Google Flights data showed return tickets for August 22-23 at around VND 5.53 million with Vietnam Airlines, VND 6.05 million with Thai AirAsia and VND 7.04 million with Vietjet Air.
Prices may change quickly depending on seat availability, booking time, baggage allowances and flight schedules.
Football tours from VND 14.9 million
Travel firms have also rushed to launch packages for fans heading to Bangkok, despite having only three days between Vietnam's semi-final victory and the first leg of the final.
Operators have had to secure flights, hotel rooms, match tickets and local transport at short notice as demand rises.
Some two-day, one-night packages are priced from around VND 14.9 million per person, including flights, a ticket to the final at Rajamangala Stadium and scheduled sightseeing.
The short booking window and surge in demand have pushed up costs, leaving fans facing higher prices for flights and accommodation as they race to reach Bangkok for the match.