I bought three today, black, dark blue, and light blue. That's enough to do blue fursuit eyes, which is the most common color I get commissioned for. :) I got them mostly as an experiment, because I can't find any information about the most important factor to me, ie. are they sweat proof. I know they're waterproof, but so are sharpies, and those proved to dissolve and run if sweated on, much to my chagrin. I'm hoping copics will be better, and I'm going to see if I can perform some tests to find out, but it's not the kind of question the copic website answers! But if the testing goes well I'm going to slowly start buying them one or two at a time until I have a sufficient palette to do any eye design I might need. Meanwhile I am sealing the HECK out of any eyes I do with sharpies.