I'd like to share my experience in finding subcontractors using your method of going to suppliers and asking them for recommendations.

Spoke to the energy supplier, they stated that the gas and electric bill will be combined on one bill.

Expect to pay about $5-7/sy for mid-grade nylon carpet, about $1.80/sy for 8 pound pad and about $4.50/sy for installation these days...Let me know if you want a reference for a supplier...

To answer your question, prime to sub (layman's term: GC to sub) is none of your business, but when you cut the check, be sure you have Unconditional waiver from ALL subs and supplier plus conditional waiver from GC.

@Austin HughesI don't know how different this is from what you're doing now, but I generally pay for materials myself (trade-account or credit card) from the vendor/supplier.

Interacting with suppliers and contractors to make sure things happen as expected.VA - Virtual assistant.

I never do fridges but always do SS appliances because they cost about the same as white from my supplier. 

Most suppliers can carry materials for 90 days, use them.Take a draw for labor from the owner.

We did find half-a-dozen of the pre-change packages at a local supplier and have put them aside for use in upcoming renovations.When it comes to replacement shower heads we have used the Delta 1.5gpm H2O Kinetic heads (here and here) and find them to work well (use them in student rentals).  

Much may depend on your market, supplier, and delivery etc...I run into whirlpool products and use them but not the brands you may think.