[Equipment] Filters in general and the ResMed 11

[Cpapian]

This is part question and part rant.  I hope that's okay. 

Why are equipment supplier brand filters so expensive?  
Am I taking risks buying after market filters from Amazon? 
Is it viable to buy some filter media and just cut to size?

I can buy a filter for my furnace for under $10 CAD it's  maybe 20" x20"

A Resmed filter is $7 CAD  and is about 1" x 1 1/2"

I quietly bought my filters when I purchased a  new mask from an online supplier.   Now Resmed has barred them from selling the 11 products.   IDKW. So I have to go elsewhere for my filters.   This has caused  me to question the whole issue.  Also, I have read some headlines about the amount of plastics humans are breathing.   I prefer to not add to that through false economy. 

So ...... what do you think?

[snorybob]

I've been using after-market Amazon filters for 5 years, change the filter every month & never had a problem.

[Cpapian]

I suspect it is something you wouldn't have noticed,  but maybe microscopic bits of whatever it is turning up in your lungs.

I'm probably overthinking this.  

Do you use one of the suppliers on the list?

[Melman]

The filter is to protect the machine, not the user. There air into the machine is the same air you breath throughout the day and has no higher content of microscopic particles.