tupperware package

Q: Is it permissible for a person to purchase a package while not having full knowledge of its contents? Also, there won't be any future disputes since both parties are happy with the sale. For e.g. The company "Tupperware" usually holds a sale once a year where you purchase a 'tupperware package', not knowing the exact quantity or type of tupperwares inside it, but the case is such that whatever you get will definitely satisfy you and turn out cheaper than the normal market value. Hence there is no question of disputes thereafter. Is such a sale permissible?