IMHO, a good parts supplier is as valuable as a good mechanic, sometimes more so. The list of suppliers you have on your email list are all good, I would also add Gernold at SLtech, there are many more. The key is to actually develop a relationship with them, they can help you figure out exactly what you need and what you don't need. Dave at Bud's has helped me save money (and spend it!) on many occaisions and he almost always considers something I had not.
If these suppliers get the sense that you are just price shopping, looking for commodities, then you will also get treated like a commodity. Not saying it is right, just is in this market. These guys have as much passion for the sl as most of us, and they really have a wealth of knowledge. I suggest you pick up the phone and get to know one or two that you can help keep you heading down the road.
Best of luck,
g
'64 230sl, fully sorted out...ooops, spoke too soon