As far as materials go, I opened up a Home Depot Pro account, so when the contractor goes to buy material, he checks out at the Pro desk.

I don't want to turn him off to the job by sounding cheap or like I don't see his value.Could I save some money buying materials on my own and providing them? 

No issues since then, but you had better take plenty of precautions secure the house and don't leave any materials or tools at the job site.

You fix it up with a bunch of free friends and some leftover material from your parent's house and get the value up to $250k with no rehab costs out of pocket (this is artistic license, but go with me here).

I have heard several stories now of landlords sourcing materials ( particularly for multifamily flips) in China. 

I would have a hard estimate together for the material but the labor would be my own time which I don't have a rate figured out for.

The seller considerable amount of the materials and some appliance which are included in the deal.

It has materials on lot it looks about 45% finished.

Reaching out to the more experienced rehabbers/remodelers, what materials did you guys choose that had a longer use and/or were more resistant to wear n' tear?

I am a software engineer, but have consumed ton of material and contents over past 6 months.