Have a look in your local Indian wholesalers/shops. You are looking for Consumer's Pride,they do colouring in a large number of different colours in 400gram/almost a pound weight red plastic bottles.Dark green,red,yellow,orange and a few other colours.(not sure of black)One teaspoon dyes a whole bucket of liquidized bread and lasts years,the bottles i have,
cost only a few quid.You can mix colours to produce brown and other colours.