Do you always go with the closest supplier or what?

If they have supplier accounts you should reimburse them on delivery for materials.

Also, is this actually cash available, or simply trade lines with suppliers/vendors. 0% intro credit card deals are usually for purchases, cash advances have %fees attached.

As a contractor I do not pass my discount on to the customer , my discount is something I negotiated with the supplier based on my buying and paying habits .

I would suggest calling local suppliers and asking them to refer you to local subcontractors for whatever trades you are looking for.

Call you local tile supplier (not Home Depot or like) and get a tile installation referral.  

An automotive body manufacturing company tied to Tesla Inc.'s California operations has grabbed a large swath of space in Kyle.Construction is underway on a manufacturing facility there, which is expected to employ 40...

I'd love to do some house flips as I feel I've been on the supplier end for a while now, but I feel I need more experience before I plunge into something major like that.  

Prefer to outsource this to a trusted supplier who has produced great results for me on my properties.

I look at direct mail marketing and other paid forms of marketing like I look at the Gold rush's of the 1800's   who made the money ... it was not the miner's it was the suppliers of the goods...