The price is for a 75cm (approximately) length. This is great for straining your wine and can be sterlised by boiling or soaking in potassium metabisulphite.
This product is sold as fit for purpose for straining wine. It may not be fit for purpose if you are buying it for another purpose.
It can be reused many times by rinsing well to get most of the pulp out, then washing with mild detergent, rinsing really well and then sterlising by soaking in potassium metabisulphite for at least 20 minutes, or some people choose to boil it.
Probably the easiest way to strain your wine using muslin is to fold it over a couple of times so there are several layers and put it inside a sterlised sieve or colander. You will find it best to leave it draining for an hour or two to get the most juice out and also to let the yeast make it's way in to the strained wine (as some of the yeast is residing in the pulp).