Here in Isaan, local workers can be anywhere from around 450 baht a day plus food and drinks, up to 1,200 baht a day, depending on the type of work, the skill needed, and the length of the job. For shorter, smaller jobs, the day rate is of course higher, but with higher day rates they bring food and drinks themselves. For normal construction work, we buy all materials ourselves from a list the workers give us. That way we know what is being used, and we pay the labour separately. 29,000 baht does not sound crazy for a small all-in job, but it is not cheap either. The concrete slab is only about 0.225 m³, the wall is about 4.5 m², plus render, door/frame, roof sheets, sealing, transport, tools, and labour. I would guess maybe 2 workers for 2–3 days, depending on the finish and how much prep is needed. Materials may only be around 8,000–13,000 baht, maybe a bit more depending on roof flashing, door quality, steel/reinforcement, cement, sand, blocks, hardware, and transport. The rest is labour, profit, and the normal small-job premium. The important part is not only the total price, but what is included. I would ask for a basic material list and confirm roof flashing/sealing, render both sides, floor reinforcement, door hardware, cleanup, and waterproofing. If all that is included and the finish is decent, 29,000 baht sounds fair enough.
