How much would it cost to build a house from scratch?

There are too many variables to answer this question. Where would the house be built? Would you be your own contractor? Do you have any skills that would eliminate your hiring subs? Land varies by location. Supplies cost more or less depending on location. Lots of work could be eliminated if you were to go modular.

for just over a couple hundred dollars you can build yourself a tree house

Figure around $150.00 a square foot and add about 18K for the basement.

Seriously? A 2 story, 5 bedroom and 4 bathroom home?!? Your looking at at least $500,000. Not to mention a tax bill of around $6000 a year. In otherwords, "If you have to ask, you can't afford it".

It will be better and less money to buy a fixer upper then building one

I am not familiar with the material scratch.Maybe you should talk to a contractor who builds houses from scratch.

Well, it would largely depend on how much square footage you have and where you build it. In poorer areas/states, it costs around 70 cents per sq foot.....in California, I am certain that building materials will run you FAR higher on costs. Many areas are running around 125.00 per square foot.

LOL, I think around $900,000 for a house of that size.

Depends on the land cost, but prefab houses that you can designe parts of can start as low as 80,000 for everything, no land.