If you're buying a new eheim, the mech and substratpro should be included.
I bought a two pack of media for the Eheim pre-filter intake. It's a little roundish mesh ball that fits right in there. Very nice! I took it out of the box and was examining it when my wife said, 'that's a potscrubber with a rubber band around it'. She was right! It's EXACTLY like the one next to our sink - but about 10x more expensiveThe only media in an Eheim that should be replaced is the disposable floss, and the cheap way to go is to buy loose polyester fiber fill or quilt batting and use that instead of the Eheim brand pads. Or bonded pond filter media and cut it to size. That's what I do.
Really? i thought you had to replace the eheim mech and the substratpro every 3-6 months or whatever... so all you really have to do is replace the blue & White sponges every few months? o_0.$50 every few months? Huh? You don't ever have to replace biomedia. Unless it starts falling apart after a decade or something.
The only media in an Eheim that should be replaced is the disposable floss, and the cheap way to go is to buy loose polyester fiber fill or quilt batting and use that instead of the Eheim brand pads. Or bonded pond filter media and cut it to size. That's what I do.
I'm a little unclear about what filter(s)? you have on the tank right now?
If you don't already have another filter on the tank, why not just run the Emperor 400 and the Eheim 2217 together?