It is great that you are trying to get them to eat what is healthy for them.
My opinion is a varied diet is the best, my birds get greens, crumbles, pellets, and seed as well as fresh grasses and cuttlebone. I am in Australia and I buy my seed from an agricultural supply . They sell in bulk and make their own mix.
I don't buy from a supermarket as I have heard some not so good reports on their own brands of seeds.
Sprouting your own seed is also a great way to get them to have a healthy diet which you know what is in the mix.
My guys love Niger seed as a treat which I buy separately and add a small amount to the seed mix occasionally.