Rit dyes can be found in a variety of general stores like Walmart, specialty stores like JoAnn's Fabrics and online directly from Rit Studio. Specialty stores are more likely to have a wide variety of colors available.
Rit dye is one of the most well-known brands of consumer dye, and can dye not only fabric but also other materials such as paper, wood, and some plastics. The Rit Studio store carries every available Rit dye product, including all twenty-seven colors available in either liquid or powder dyes. Rit Studio also sells compatible products, like Color Remover, Color Fixitive, White Wash, and Fast Fade to make a variety of effects possible for the consumer. In addition to the smaller sizes also sold via craft and department stores, they also sells a "professional" line of dyes, which are available in bulk amounts.
The selection at specialty craft stores, such as JoAnn's Fabrics and Michael's, may vary depending on the size and layout of your local store. However, they are still likely to have a wider variety available than the department or general store option. Calling ahead can help establish whether or not a particular store has a specific color. The Rit Studio website offers a Store Locator function to help identify nearby stores.