We live in Preston, just west of you. For seeds (and suet) we patronize the
Grange in Issaquah. The prices are competitive and it's NOT a big box
store.

We ask our birds to shell their own black oil sunflower seeds - chips may be
preferred, but gosh.... Whole seeds in 40# bags bring the cost way down.
In spring/summer/fall, we put out niger seed for the siskins and goldfinch.
The flickers and various thrushes go for the millet (we feed separately and
not as part of a mix, which helps avoid lots of waste). The bandtails like
cracked corn. All of these are available at the Grange, and bought in bulk
are very reasonable.

Not sure what your yard situation is, but consider native plantings to
attract a greater quantity and variety of local birds. Even a small yard
has room for enough to make a difference. Check out the native plant
resources on the web. And never underestimate the value of a water feature.
Our small garden pond has attracted a heron, kingfisher, a variety of
warblers, and western tanager - all of whom pass on bird feeders.

Good luck
Janet Ray
Preston.