Sorry can't help you with an organic one I buy a good quality seed mix for my aviary gang. Generally use Haiths or Bucktons to feed them and then add to that millet on the stalk, egg food or egg biscuit, plus iodine blocks (very important for budgies) they have cuttlefish and they get fresh fruit and veggies. They get dandelions, shepherds purse, chickweed, assorted grasses, apple branches plus willow with the leaf still on. You can also feed Amaranth, barley, couscous, flax, wholegrain pastas, oat, quinoa, whole-wheat, wild-rice, whole rices, Bok-choi, broccoli and/or cauliflower leaves, cabbage leaves, collard greens, kelp, mustard leaves, seaweeds, spirulina, water cress! Heaps of fruit they like too.
I once bought a packet of Trill to see what was in it and was mortified to find it's mixed with grit in the box
fair freaked me out.