All of this stuff makes me laugh? Like diatomaceous earth is the only thing in the hobby that can cause cancer if you use it wrong... the plastics in some cheap chinese parts appear to contain massive levels of Tin, calcium hydroxide, GFO, who knows what is in the hot supplement of the day.
You can still find these filters if you go to in-person aquarium club garage community garage sales, hit up the freshwater places with large accounts, eBay sometimes, etc. I found 3 of them in the used bin of a local store a year ago and mailed them to a guy on here.
You are gonna have to work - the online and easy stuff is all gone.
If you have a big tank, a pool DE filter and a trash pump work better... but probably $500 to get started.