Yes you may be able to build a building for that.  But that would not include 1 megawatt of power distribution inside of that building.
(If it does, I would love to know where you are buying your electrical gear)   
Power distribution is the highest cost.  Then if you were to include cost of stretching your conductor through the building to the point that
it can be used will only continue to increase costs.

I will be the first to admit that there are advantages to each solution.  The electrical gear inside of our container is all UL listed as well as rated at 415v.
I have built a couple of bitcoin "data centers" in existing buildings, 6MW worth, and I can tell you that by the time we got power into where it needed to be
neither of them came close to what we can build these containers for.  I am sure there are some exceptions. 
But that is one of the reasons that we decided to get into this business. 

Thanks for your comment on how nice they look.

Thanks for your comments.

Yes - One of the things that we did to reduce costs as well as space that is taken up by PDUs was to hard wire our power cords.  The other advantage is that we have the cords cut to length for the given area that a miner would go.  This also reduced the amount of cord that would have to be coiled up or left hanging which would be in the way or block much needed air flow.  As you mentioned however, we are not locked into that as an only solution.  We know that there will be customers that just won't like that and will prefer PDUs or outlets.  And that is ok, because we can do it however you would like it.

My goal is to build something that your happy with and can depend upon.

The racking is custom.  It can be made to be adjustable, but typically our clients have specified what they wanted and that is how we have built them.  This enabled our client to be able to maximize all of the available space for miners and power supplies.  Our cost still comes in very comparative to if we were to go to a Costco and buy shelving that would take up too much space and not allow for the same number of miners.

Those are all very good observations.

Price range.   As a ballpark figure, a  40' 1 MW container container starts out at $135k. (Fanless version). 
 
Also keep in mind that our fans are high pressure fans that are designed to pull the correct amount of air required for 1MW of heat as well as accounting for back pressure that will come from pulling air through filters, louvers, and increasing pressure as the filters get dirty.  If the fans don't have the proper rating (hp and blade type) they will become useless as your filters get dirty.

The Protocube is either a 10', 20' or 40' mobile crypto mining container.
We have built 11 of the 40' units, each with 1 MW of power distribution inside.
I would love some feed back concerning our units.
The website is https://protocubes.com

We can build them to your specifications -
With or without exhaust fans
Evaporitive cooling
Warm air recirculation (for cooler climates)

Thanks for your time -
Steve -

Here are some pictures -

https://imgur.com/6OwnRWs
https://imgur.com/sjpj9SD
https://imgur.com/8Urw883