Hi Shaun , for the small 50g containers .. if you search ' acid dye feathers ' on ebay there is lots to choose from .
About two years ago i got to do a hotel that had brown nylon carpets all dotted with bleach spots from the cleaning staff over the years ( it seems very susceptible to bleaching anyway ) so i needed a large amount of dye , so i found Cobb carpet supply in the states sells 1lb containers for about 14usd , i got a few primary colours there .
I dont do a lot of dying , i def not proficient in it , although it would be nice to be . I am a chancer though so il usually do something to remove or disguise a permanent stain .