Just to add my 2 cents' worth... when you have a bunch of rules and laws (and ISO, QS, TS, etc. certainly have them) then it is easy to become legalistic. The purpose of certification is to ensure a company has good solid practices and processes. If a company can do that without certification, then certification is of little to no value added to that company. The goal of any company should still be providing the best quality at a reasonable price that mutually benefits both the customer and supplier. In my innocent days I used to wonder how did Honda and Toyota ever built quality products in the early 1980's without ISO. Now I know, they had a system that was beyond what ISO/QS can ever dream up.
Like Marc says, if you are dropping a supplier just because they don't have a ISO/QS flag flapping in the wind, then shame on you. I think we all need a sanity check on this certification stuff.