I agree with scythe; if you give something out for free, it has to be something that you're okay with people taking carelessly and then throwing away.
It's absolutely a good idea to have a freebie to hand out, though! I've done this as a comic before: four "pages" that are just a single sheet of paper folded in half with samples of the comic on it. 8-14 pages given out for free seems too much to me.
The question of whether such things will sell honestly depends on the con -- at some cons minicomics are expected, and people show up expecting to spend money on that very thing. At other cons, it'll be a hard sell. My experience has generally been that a little A5 mini without many pages is tougher to sell and kinda needs to be under $4, but I don't know how that translates outside of the US.