All you have to do is go in pick out the tank and if he wants to charge more then point out that it is a instore advertised produce. Under the comsumer protection act he has to give it to you for the posted price, for that matter if there is a lower price anywhere visable for that product he would have to honer that price. I would also let him know that you took a pic with your cell camera to if he wants to argue the facts..