Is it possible to buy more individually!

Best pens out there! (This box is on my wish list ;-))
I use it for years, male also in the artistic field with it. There is a wide range of colors, as you can see. But what is especially in the art world especially important: One can each color buy more! Each color / pen has a number, with which the color in the well-stocked stationery stores / department store, etc. buy more (or order the net) can!
That definitely with the cheap pens you can not. And, also important, these pins are much more light stable than the No Name Goods! One has to images that have been painted with these pins much longer pleasure!
Possible stuck paintings behind glass in a frame and still hang on to places in the room, where no sunlight hinkommt- sharpie pictures are sensitive which light comes: still a final tip.
Or, better yet, good color copy of the picture make this hang up and leave the original in the wallet!