Below is a link that describes passive vs active vs material participation.

Preferably contact them by e-mail as we are not allow to self promote.

You may want to read materials about "networking for a job":)

The quote was $5352.00 ($3,650 for labor and $1,702 for materials).

This diversity is reflected in their housing preferences and priorities, driving demand for inclusive and culturally diverse communities that celebrate diversity, promote inclusivity, and provide equitable access to housing opportunities for all.In conclusion, the Millennial generation is reshaping the housing market in profound ways, influencing everything from location preferences and home design to technology integration and community development.

I just wanting to make sure he's not purposely overestimating material and then keeping it to use on other jobs.

What are the industry standard marketing and design tools people use to create marketing materials and OMs for commercial real estate?

I will spec materials/colors/repair method when I feel it needs to be done a certain way or I want something different/special.  

I've heard a tremendous amount about using promotional 0% interest business credit cards to fund buy-and-hold investment deals.

Add into the equation the cost of materials and it makes sense that builders are finding ways to cut overall build costs and one of those ways is to buy land cheaper.