Beowulf, try the lactose free milk! LOL
Regarding the OP's question, we use way too much seed each year. I average about 15 to 20lbs a day right now, although we do use less in the summer, I'd say about 5lbs to 7lbs a day in the summer. We use mostly black oil sunflower, but also some smaller seeds, and I buy peanuts (shelled) as well. So far since November I have used at least 400 lbs of sunflower, 200 lbs of peanuts, 200 lbs of niger seed and over 50 suet cakes. Add to that the other seed mixes we use for the smaller birds, you get the picture. (I get it all at wholesale though so the cost isn't as bad as paying retail).
Yes, it's a luxury for us, we don't go out to dinner, or travel or gamble or anything. I love being outside and the birds are part of it for me. It got this way years ago because I worked beside a warehouse that shipped bird seed among other things and they would give me about a quarter pallet of broken bags a week for free. Back then I had about 30 feeders all over the place, easy come easy go I guess.