I get a ten dollar bag of ten pounds of black oil sunflower seed. It lasts awhile and all birds love it. Many inexpensive brands have many fillers that birds don't like very much.

Could you tell me what store, or type of store you found the sunflower seeds?

The first thing you need to do is look at the ground underneath the feeder and see how much seed waste is being generated and not being eaten by your feathered visitors. Secondly, how big is your feeder?
I have progressed from buying small but "cute" feeders to one bigger one that I've modified by adding a deeper feeding tray underneath. Much more seed is being eaten now with a LOT less being wasted by being tossed out of the tray by the few stupid birds that have to dig through the whole mess to get that "special" seed that they don't want any of the other birds to have.
I buy both black oil sunflower seed and a 'Wild Bird Mix' (25# of each), both put out by Purina, and mix them together in one big plastic tub with a varmint proof snap on lid. While the Purina seed is a bit higher in cost, it's clean and there is no waste (seeds that the birds won't eat, bits of stem, hulls, etc.)
Instead of buying at the grocery store where the product may have been sitting on the shelf for an extended period and is usually higher in cost, check Wal-Mart, Lowe's, Home Depot, and feed stores that may be close to you. In addition, buying larger amounts, ie: 15# and up in a bag, results in a lower per pound cost.
Hope this helps.
Steve in TX

Thx for the info---I'll do that. Do you offer suet too?

I've tried commercial suet cakes of various blends in the past with no luck but that's probably due more to the types of birds that usually visit my yard than any fault with the suet.
I've also given up on Niger (thistle) seed in my immediate area but hung a mesh "sock" filled with thistle seeds in an area across town where I often go to photograph winter birds and it was emptied in 2-3 days.
My feeling is that, while X number of species may be in one area, that does not mean that the same X number of species might also be in a similar area even a few blocks over... With each species somewhat preferring certain "favorite" foods, one often has to experiment with different mixes or food "types" to gain the advantage of most birds attracted with the least amount of waste.
Hope this helps...
Steve

I should probably make a disclaimer here and that is I'm not necessarily advocating everyone buying two different 25# bags of birdseed and mixing them instead of smaller bags that may better fit a person's budget or storage space. The bigger bags just happen to work best for me and I have the storage room in my garage to keep the excess until it's all used up, typically about every 45 to 60 days.
Just didn't want to infer that I'm doing something that others are not able to do because of various financial and/or personal reasons. I feed at least every other day because that's how long it takes for the feeder to be emptied in my yard so the bigger yet more initially expensive bags/amounts just make more economical sense in my particular situation.
I apologize if the information in my previous post inferred anything other than just trying to be helpful to the original poster.
Steve

This post was edited by TXSkeeter on Wed, Oct 2, 13 at 10:01

Thx for the info; I happen to have room for a large can for birdseed, altho my feeders stay full for at least a week, but with more sunflower seeds in the mix, I assume many more will come, and I do hate buying seed constantly. I live about four blocks from a river, and when I walk the block closest to the river, the birds are so noisy it sounds like a jungle. So most of the birds must stay close to the wooded riverbank.

We mainly have chickadees and other brown birds, but I do get house sparrows with a rosy head and breast, for a bit of color (this is Oregon). Now there is a large flock of birds wildly feeding on my fig trees, and I can't identify them.

I followed your suggestions and found large bags of mixed seed and sunflower seeds at True Value Hardware (a chain store with excellent prices), mixed them together in a large can, and now I have more varieties of birds than ever before. The sunflower seeds do make a difference. Now, tho, I've seen a hawk swoop down twice on one of the feeders. I've never seen that before, and I don't know if it caught a bird, but it's frightening.

Anyway, thx again for the tips.