Uhm... It's quite easy to craft... Why would you want to buy it?
I'm just curious, not trying to stir anything up.
Maybe they're not level 15-20+ yet, and/or don't want to put the points in Survival up to 40?
My Survival always starts at about 11-15. By lvl 15 I might (emphasis on might) have bumped it to lvl 25 w/the help of a couple Books, but often I don't bother.