Not sure whether you are making these kits so you can have tinder stashed in many places around your home, or whether you are looking to sell kits. In the first case, what you have been told here, one tea towel or half a pair of charity shop jeans will see you good. Knowing how to make the char cloth is part of the skill set involved in making fire with flint and steel and is good fun to experiment with.
Based on what you emailed to Ogri though, it sounds like you are fishing for supplies to sell on, which is a bit of a cheek for a first post. If you are looking to sell kits, you should know that the people most likely to be making char cloth in bulk are your competition! As such I doubt that they will sell it to you cheap, and I would be dubious as to whether you get the best product.
Regards
