Costs of feeds

Am I being mean, we retired in the middle of the recession so our pensions are small to say the least. I do not want to stop feeding but having moved to the coast of Scotland recently feeding bread is not an option - Seagulls! In my feeders I use a mix of sunflower, oats, dari and millet huskless to save mess. To this I top up with kibbled hearts, kibbled maize and kibbled peanuts. Then I add a dash of mealworms and at the moment fruity suet bits. They eat it all up - trouble is I cannot keep up with them in terms of affording it! I have tree sparrows, house sparrows, blue tits, great tits, coal tits, chaffinches, robin, starlings on the hangers - two one for small birds with cage for squirrels but to keep out the bigger birds. The blackbird, collared dove and the odd pigeon eat up what the starlings chuck on the ground. I also top that up with handfuls of a table mix. Any suggestions for a cheaper mix that will not loose me the assortment of birds that are outside my kitchen window all the time except during Birdwatch!