Do you mean a typical western style funeral?
Or a typical Buddhist cremation at a temple which offers such facilities?
If it's a Buddhist creamtion the cost is the same as a piece of string mostly depending of extrensions of number of days, parties etc.
My Thai, at my requestlooked for the cheapest near us in Chiang Mai.
I did, some time back, tell my son 'keep it totally simple, no extra days, no parties, just the cost levied by the temple for the burning'.
Best he found (just 1.5 km away) was 30,000Baht. But he also found there is no standard pricing.