Lots of people give dried greens, and dired fruits to their birds. Here is a link to one (I have the product here in my house actually, but havn't opened it yet, but I know people on this forum use it because this is where I got the info on it - here is a link so you can see what it is:
[ame="http://www.amazon.com/HIGGINS-466342-Attack-Greens-2-Ounce/dp/B001LDE1UA"]Amazon.com: HIGGINS 466342 Higg Snack Attack Greens and Herbs Bag for Birds, 2-Ounce: Pet Supplies[/ame]
And here is another with fruits and vegetables as well as seeds:
[ame="http://www.amazon.com/Higgins-Snack-Attack-Veggies-10-Ounce/dp/B002IUN7LY/ref=pd_sim_petsupplies_2/178-5871081-9767637"]Amazon.com: Higgins Snack Attack, Fruit and Veggies Small Bird Treat, 10-Ounce Bag: Pet Supplies[/ame]
As you can see the prices are very reasonable.
Millet. I buy organic millet from Dr. Fosters & Smith and it's pretty much agreed that all birds love millet. Here is a link that I suggest you take a look at:
All About Millet
Millet is just one of those things that you give as a treat rather than as the main diet. It does have a lot of fiber and a lot of carbs, but is rather nutrient poor - but it has a lot of uses, particularly if your bird isn't feeling well you can often coax them to eat some millet to get something into them, and it is very useful to feed to chicks when they are being weaned. It's an important part of the diet but generally only as a treat so a small part of the diet. That link explains it quite well I think.