When I saw $30, I was fishy, but looked.
"FIELD COLLECTED SPECIMENS
[...]
GREAT LOOKING COLORS
VERY VARIED GROUP OF COLORS, SOME VERY LIGHT AND SOME VERY DARK DETAILED
ALL ARE IN GREAT SHAPE AND EATING MICE!
THIS IS THE BEST DEAL ON KINGSNAKE!
SOME EXCELLENT BREEDERS AND SMALLER GUYS!"
Field collected is wild caught. There's nothing that says they're been treated for parasites, ect.
Good colors are both an opinion thing and usually a captive bred trait, and if they're field collected and breeding, I highly doubt they've been bred by the people who have them right now or they wouldn't be 30 bucks.
And... best deal on Kingsnake? What, it's hard to edit "fauna" or something? Plus, the all caps just screams no.
It could be a GREAT deal for a legit thing, or it could be a total rip off. Sure, not a whole lot of money being spent, but I don't think it's worth the possible trouble. The poster does have a good trade rating, so see if you can find info on them, but this looks like a "buy at your own risk" thing to me.