This is what I feed my birds.
My macaw gets "Pretty Bird" pellets. It's what her breeder weaned her on and while I'm sure it's got it's critics, I haven't seen any ill effects from her or the place I use to work that fed them. I make sure she has access to these at all times.
The Grey's have Harrisons Course pellets, it's what they are use to. I am now mixing some Pretty Bird in with it to see if they like that as well, so I don't have to buy two seperate kinds.
They also eat "bountiful harvest" from mysafebirdstore. I gave some to my Macaw and she ADORES it, so I bought a 10 pound bag that will hopefully last me two weeks (hopefully, we'll see with 3 birds eating it)
Every morning I give fresh fruits and veggies. They have access to them for about two hours before I pull them out so bacteria doesn't start to grow. The fruits and veggies vary as to whats in season. I like to buy the "seasonal fruit" pack from walmart for 8.88 that has grapes, melon, strawberry and kiwi already sliced up. Then I chop up veggies. Occasionally i'll add some pasta, eggs, or grains to mix up.
In the evenigns I like to give treats. Macaws NEED to have some fat in their diet so I make sure she gets at least two nuts, like broken up walnut (she hasn't figured out breaking shells yet) and an almond. Depending on what I have for dinner I'll share that as well. If I make bird bread, i'll give them that too

piggies that they are.
There is always waste when it comes to fruit and veggies.
Pellets are easier because you can leave them in the bowl and just refill (though my macaw likes to grind hers to dust.) Your bird may only like Zupreem (i tried giving it to mine and she didn't like them.) But definatly keep that until you've decided to change her pellets, and make sure to mix so she can get use to them gradually (and see if she even eats the different ones)
It's trial and error, but you'll figure out a good feeding routine and learn what you need to buy.
As to where to buy stuff, nuts you can buy from the grochery store. I like grabbing the bags during the holidays and freezing the extras, they're cheaper that way. I go online to buy a lot of stuff though and check prices at amazon then online bird stores and things like that.
