Using this new build as an example: https://www.redfin.com/IL/Chic... . It's two units and they're asking $1.4m. The top unit is a 1800sq ft. 3/2 simplex. Bottom unit is a 3500sq ft. 4/3 duplex down. Sold as vacant land a year ago for $242k. I looked up permits and the cost to build is listed as $465k. Is that $465k really what it cost to build this entire new construction of 5300 sq ft. total? Does that include all their costs, or only certain things? If the $465k is accurate for all in, then that's only $87/sq ft. which seems insanely cheap...Or is that $465k cost listed in the city records just an estimate that the developer has to provide to the city and it could be way off?

If the $465k for building costs is accurate, then that brings total cost to $707k (242 land purchase + 465 building costs). What other costs have to be considered when looking at the fact they built this new and it took a year. I assume just property taxes, insurance, and mortgage interest right? Since this was vacant land the prop tax are super low. Is it fair to say the carrying costs for the year were probably just like $5k-$10k? If so, then let's say the total cost all in is $720k. Is this likely on the right track or am I way off?

I assume this has to be a developer or investor that already has a team that took this project on right. So are they really going to profit nearly 100% before tax if they are able to sell it for $1.4m? Assuming $1.4m sale less ~720k costs. That seems crazy. Or am I missing something. Assuming the sale proceeds all go to the current owner of the property who did this new build, if that individual has to pay taxes on $700k of income gains, I guess that's pretty high at maybe 35% or so, so say $240k goes to taxes. They still walk away with $460k profit here? Am I on the right track or am I wrong anywhere in my numbers and thoughts.

My last main question is, let's say a normal person like myself had bought this vacant land and wanted to build this new 2 unit. Without any connections or a team, how much $ would I be looking at to spend to commission this project if I wanted it for myself. I have to assume it would be way less than $1.4mil which is the asking price, but I also assume there's no way I could do it for $465k since I am guessing the building costs are only that low because whoever owns this property currently has a team in place and can do the actual work/get materials way cheaper than I could as a normal consumer? And as a normal person I would have to pay a premium for a GC/sub-contractors right, whereas whoever did this is probably a GC themselves or doesn't have to pay those premiums? So let's just say I bought this land for $242k myself and I wanted to build this exact multi. How much would I have to pay a GC to make it happen? $700k? How do I go about thinking about it or determining how much more it would cost a normal person compared to a developer/investor etc. 

I'm also still kind of shocked and thinking I must be wrong about the costs since this building is 5300 sq ft. living space and was able to be done for $720k ish all in? I just think that's too cheap right? Or is that really how much of a benefit a developer or someone in construction can get a project like this done for? And then they can just charge a premium to public buyers for the 2 units..honestly even at $1.4m, this only comes out to $264 sq. ft which still seems pretty cheap compared to other things I see in Chicago for higher end units/sfh's ($350-$450+/sq ft)

Would love those of you more knowledgeable about new construction and the finances around real estate to chime in here.