I worked at a disc drive manufacturer for awhile. IBM was a big customer, they sent in teams to negotiate the quality higher and they sent in other teams to negotiate the price lower. The owner of the disc drive place eventually wished he had never heard of IBM. At one point we had a rework line just for IBM and some days we were shipping drives that worked to IBM and all the rest of the stuff got shipped to Tandy, etc.
Big customers can negotiate just about anything with a subcontractor, you have to watch out. You can get car tires from a discount house that have the same name and very nearly the same part number as the tire you want but it will be a negotiated knock off, made by the same manufacturer that you wanted the item from in the first place. It foils all your research, you think you are getting a great tire because all your research pointed you to that item, then you shopped for price and bought a piece of shit. I had four blowout in a year before I was savvy enough to know the difference.
If nobody can compete with Wal Mart in the cheapness and low quality arena then all you have to do is stay away from the place and you have a reasonable chance of getting good quality.