The (C) Disney/Sedesma SA pins from Spain. They are commonly called "cheap pins" since that is what they are. The metal is thin, lightweight and almost always has a painted look.
So don't pay much for them. They are not what you think of as Disney quality pins.
Most of us have some in our collection. They do at least have different characters and poses that regular pins do not.
But don't be disappointed when you see them and can compare them to a regular Disney pin. There is a reason they are cheap.
Also, if your trip is quite aways out, wait. Disney can change their pin trading policy at whim. I would hate to have anyone buy a lot of cheap trading pins, only to find out the trading policy no longer allows Sedesma. It's a gamble. It may never happen. And yet it may.
Sale pins are at the outlets -- at Belz and Premier, closer to WDW. They have full price pins. But randomly have a limited stock on sale too for around half price I think.
Best bet of all is keep an eye open on Disney Direct. Twice a year they sell GOOD pins for good prices. There was such a sale probably less than two months ago. It will be awhile before the next one.
DON'T buy any Name pins. (That have a person's name, or #1 MOM, etc.) You will see those cheap. But they are not tradeable. Sometimes you will find a CM who will bend the rules for kids, but....