My only qualm is that since these are open source designs, printing them in their unaltered form should be a public service and not a way to profit. I don't think each sticker takes $4 to make, and I may be wrong there, but I certainly know enough stamp(s) to mail a sticker wouldn't add up to 99 cents.
I am not sure what to say about that. Is profit a bad thing?
Do you have a different idea of public domain then I do?
You are the first to complain about overly expensive 99 cent shipping.
You can do it for less if you want to. I am not sure that other sellers will put out the same quality that I do though. Mine are not home printed. They are on vinyl, UV protected for the bumper stickers and squares.
While I am not required, I tend to take the profit from one run and use it for another, so after I sell a bunch of these I am going to move on to a standard white backed sticker for counters and inside.
Oh, and I give away promotional stuff all the time. Stuff that promotes bitcoin, not my own store.