Here's that link you were talking about
Beginners Guide to Filter Media - MonsterFishKeepers.com
We have 2 Ocean Clear canister filters that we had to "design" our own media for. The filter inserts for these things are just way to expensive. So using that link, we did a bit of extra research.
At places like Hancock Fabric stores, you can get a monster sized bag of 100% polyester fiber fill for pillows. You can also get this in a roll for doing mats. It's the same stuff you would pay twice as much for as filter media. I think we spent under $10.00.
The potscrubbers (we use the plastic ones, not the green ones) are mainly for biological and I believe they do some mechanical. They can trap larger particles. As for water polishing, I'm not sure if they would do that as they do allow so much movement that I don't think they can catch the finer things.