You can buy just about anything but love from Taobao. I had no doubt i could find a replacement for the torn and tattered sieve on my Coffee plunger, which i use daily for making Kopi. The keyword to search is “咖啡滤网片”, and i managed to find this seller.
I guess the sizes of plungers must be pretty standard, as one of the three sizes available for the sieve was a perfect fit. The diameter of the sieve has to be slightly bigger than the actual diameter of the plunger flask, since it curves upwards at the outer edge. At 3.8 Yuan (S$0.80) per piece, it is dirt cheap. With the availability of this sieve from Taobao, i can imagine my plunger will last me forever.