More description please. Won't follow the link you posted.
If it is amazon gift cards and the sell is selling it for a very low price, then high chance its a scam. If he does have some reputation and has been selling for many days, then highly likely those are stolen or cracked gift cards. I would suggest not to buy those if you don't want to fall into trouble. Remember, if some offers are too good to be true, then there is actually something fishy.