None the less it is an important measurement so here is a rough estimate of cost per square metre different types of houses may cost you. Project Homes (basic) – $620-$780/square metre. Project Home (deluxe) – $1,000 – $3,000/square metre.Custom Built Homes – $1,500 – $3,000/square metre.he cheapest you can build a house for in Australia is somewhere around $155,000. Front to back slope – $6,000/metre slope Side by side slope – $9,000/metre slope. 4 bedroom homes range from $130,000 (160sqm) to $190,000 (300sqm) when looking at the most basic range of properties.