I need to get some essentials, like a pillow, comforter, towels, t-shirts, workout clothes, etc, and don't really feel like paying mall prices to get a towel that says Emporio Armani.
In the shopping arcades under Central Station there are a couple of haberdashery shops which should stock Dylon dyes. I bought one once from an artists' materials shop, but sorry, I've forgotten which one.
Empik has fabric paints, if you're brave enough to try one in your washing machine :-)