Dennis,
I buy my bird seed at Skagit Wild Bird Supply in Mt. Vernon.
It is close to me, essentially on my way to 2/3rds of my local
birding locations, and the people there are both knowledgeable
and friendly. Does it cost more than Costco? TBH I don't know
because I've never priced it at Costco ... but probably is less.
Is bird seed something I budget? No. Is it expensive? I buy
it for the birds ... not sure how to put a monetary value on
that. *G*
- Jim in Skagit County