I wish you had told me that before, so I would have known to be upset when I got CDs in thin cases during the first swap.
My post office had small boxes that were designed specifically to fit CD cases. They cost more than you'd expect to pay for a piece of cardboard. I don't remember how much more.
I also bought label stickers so I could print out a tracklist and put it on the CD itself. You can probably skip that part. Most of the discs I saw just had a picture for a cover, and a printed or handwritten tracklist, on a piece of normal paper, plus a label written in marker on the top side of the disc.
Not counting the cost of buying the CD burner, but counting the fact that I had to buy more CDs and labels than I actually used, I would guess that the whole thing cost me about $30. I probably could have done it for $20. This time, since I already have discs and labels, it might cost me under $10. I don't know what these numbers mean in practical terms. I can tell you this is more money than I would have spent on anything when, say, I was in high school, but now that I actually have a source of income, it's not a big deal.
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The what mentioned above is total fiction. Please don't take it seriously!