I just called Mityon again, and asked why they advertise 10K discount, but offered me only 5K.
The answer was, 5K if you pay cash, 10K if you pay in installments (read pay 50% more for the same bike 😄).
Only in Thailand. Thanks anyway for the heads-up, I think 92.300 baht everything included is to be considered, over 74K + the extras for a +1 year old bike, even if it has only 5000 km on the clock