Just a thought, instead of paying 15k upfront, is it not better to buy materials directly online and ask the contractor to take delivery of the same and we pay only for the labor and services portion? 

Last time we had one (in 2010) the labor and delivery was $7,000. 

There's so many administrative forms to clear when you move out, move in to a new suburb, dealing with my kids' school, arranging the deliveries, in between managing our vacation home, it gets quite crazy ...Cheers and talk to you all soon, Jasmine

Think about taxi drivers, UPS delivery, bus driver - and even contractors, for some examples.

This is usually negotiated and spelled out up front and either can be the case and its likelihood of owner purchase and delivery may depend on the type of item. 

We have tried the add-ons like grocery delivery, tube rentals for rafting nearby, charcuterie boards, etc and have gotten ZERO interest.

One is at $100 per square foot including build and delivery, the layout and finishings are very nice.

They also included delivery, setup (unloading from the truck and setting on the foundation) and close up of the home which is attaching the module as, finishing the siding, all the interior finish work, patching cracked drywall, installing carpet, etc.

PM likes to order from one of the big delivery companies HD or MD Supply at 5-20% above retail or a "deal" that they have with a company like GE.

Of course the person using your mail delivery service would be notified when there is something there and who its from, minimizing traffic.