I booked an AirAsia flight on 3/31 for Buriram to DMK departing on Sept 5 and returning on the 8th. The cost without the payment processing fee was 2,284.62 baht. I just checked the price on Kiwi for the same flight times and seat selection. Here is the Price breakdown.
Your final price may consist of multiple one-way journeys purchased in different currencies. Exact prices may vary according to exchange rates.
Passengers 1,899.03
Base fare 1,728.80
Kiwi.com service fee 171.01
Seating 1,456.90
Seating 335.01
Kiwi.com service fee 1,121.89
Total (THB) 3,355.93
Including all taxes, fees, surcharges and Kiwi.com service fees.
No payment processing fee but a 1,121.89 fee for seat selection.