Budgie tonic mix is usually individually weighed and bagged up in small pet shops. Sold in 1kg bags.
Just go into your local pet shop and ask if they have it. The smaller shops usually have many different caged bird seed and millet in bags from plain millet, to canary mix, finch mixes and various others. Budgie tonic mix is specially blended to have many different seeds in it. They basically make up smaller bags from the large sack since some people don`t want or need large sacks of it unless they have an aviery!