In addition to shellac in dissolved form, which you can find at most paint stores and home centers, shellac is also available in flake form for you to dissolve yourself in denatured alcohol.
One of the advantages of dissolving your own shellac is the variety of colors available. For example, in the accompanying photo, from top left to bottom right, the colors are super blonde, orange, button, garnet, extra dark and seedlac, which is unrefined shellac.
Keep in mind that the flakes shown are much thicker than the shellac will be when used as a finish. So the colors you get on the wood aren’t as dark.