The reality is we tend to bash vendors here if we are not happy with a certain thing, and then tend to keep it secret when we find a supplier that has what we want at the cheapest price.
I have shared on many scattered threads over the years where I get my postcards printed in the past, as well as my banners for my trucks, my foliage, my clips, my yard signs and most other items.
It is true that all this info can be used by my local competitors to remove some of my advantages. So I am sharing it less these days. But I still try to contribute to threads and answer install questions, as to this is HOW you do something, but not "where" do you buy that.