$20 is a ton for a cleaning cloth, but a small price to pay for consumers of apple products.
Here is the alternative (personal experience) 1. You search on amazon 2. Get presented with 1000 products 3. Read some reviews, wonder if this is the best product for your iPhone, will it work on the laptop 4. decide you don't really need a cleaning cloth
The apple solution, solves your problem for a price.
I haven't bought the apple cloth, but have and am considering it.