Say you want an aqua clear 500. Its like 80 bucks for the one at petsmart. But if you go to the petsmart website http://www.petsmart.com/global/produ...xt=filters&N=2. You click on the Aqua clear 500/110 and add it to your cart. Then go to you cart on the top right corner and click on it view you items. Then you print out this page.http://www.petsmart.com/global/order...=1153265329884. And when you go to petsmart to buy this you give them the printed page that says you buy it for $39.99. Trust me Ive done it. I did it one both of my filters and I saved a bunch of money. You can do the same thing with everything else just do exactly what you did with the filter and just print it out.