I used a few of these very simply linked together in the crystal extravaganza bracelet I made Saturday, but I'm anxious to work on some more complex chainmaille designs.
There are 300 in the tube I bought, but I'm not sure how many are typically needed in chainmaille. I also recently found a jump ring tool that you place on a finger (below), hold a jump ring with pliers in the other hand, slip the ring in a metal slot on the tool and open or close the jump ring. Pretty cool! Saturday was the first time I used the tool and I can see how helpful it would be for working on larger designs. It does require a bit of caution not to scratch the color.
The local bead shop also had these in purple, gold, copper, silver, black, blue, red and orange in this size and lots more in a larger size. I am guessing that buying in bulk is probably your best bet if you are planning to become an experienced chainmailler. For now, I'm hoping I can finish a piece with this one tube.