Build Your Own Starling/Grackle Proof Feeder
This feeder combo will keep out european starlings, grackles, cowbirds, and red-winged blackbirds while still allowing goldfinch, house finch, chickadees, red & white-breasted nuthatches, downy woodpeckers, pine siskins, dark-eyed juncos, sparrows, and other small birds to feed. It is a great feeder to get if any of the first four birds listed are dominating your feeders and scaring off the more desired birds.
Please note that this feeder will also keep out some birds that you do want to attract, like cardinals, hairy woodpeckers, red-bellied woodpeckers, and blue jays. In order to keep attracting some of these birds while still discouraging starlings and grackles, get the Recycled Upside-Down Suet Feeder for woodpeckers. And to keep getting cardinals, try any Tube Feeder with a Seed Tray and use Safflower.