The nation wide list suppliers go for quantity over quality and I bet if you concentrate on your local area you can build some niche lists that everyone else is not marketing to. 

We buy windows from the supplier ( ABC inc) .

In broad strokes you need 1) lead relationships (wholesalers, agents, etc) 2) money relationships 3) contractor relationships 4) supplier relationships 5) sell side agent Let me know if you need any recommendations for any of those in Los Angeles County.

I'm considering when to begin using property management.Having said that, I find in my day job this same problem dealing with suppliers.  

It has been helpful for me to choose Roofers and Roofing Suppliers who know each other. 

Just search REIA and put in your city.Most groups are a solid mix of investors that wholesale, flip and buy/hold, as well as suppliers and contractors.

The cabinet supplier can refer you to installers for cabinets and countertops. 

It is about what work is needed and how you negotiate with the contractor and supplier. 

I'm at the trim phase on four specs right now and have been considering adding some new suppliers for lighting fixtures and plumbing trim.

High-Density Material• Bamboo is the hardest flooring most suppliers carry.