are there warehouses ... direct window suppliers, direct flooring/doors/fixtures without home depot or someone like a Pella or Overhead Garage Door?  

We have a friend with a rental in Mesa along the following lines- built in early 90's all the fixtures are polished brass vs the brushed nickel you see now.  

In Denver water tap 3/4 inch gives 43 fixture units so, you can just squeeze a 4plex on one tap.... costs : 3/4 water 25000 plus install, sewer 12000 plus install.... so $50000/3400 sqft would be$14.70 / sqft... you may have accounted for this already..  

I do all this for the price of a cup of coffee at Starbucks.

To be honest, I just don't think it was my cup of tea.

Some people may call you out for the light fixture being too taste specific in the dining room, but it doesn't bother me.

So in theory what might seem like a huge payment in today's dollars might be equivalent to pocket change or a cup of coffee in a decade or two due to inflation.

It's pretty hard to get a cup of coffee for " no money".

I believe the permit is expired but the only items left to do in the unit are flooring , finish off 3 bathrooms, applicances, fixtures and trim.

Most flippers are going to at least add paint, new floor and possibly add new fixtures, and update the bathrooms and kitchen.