More expensive than sunflower seed, safflower's strongest selling point is that most squirrels, crows, and grackles don't like it. They may find another food source if a favorite feeder only offers safflower seed for a week or two. Commercial mixes attract the widest variety of birds. Shop around to get the best price and compare labels to get the best value. Some mixes contain grains and seeds that birds don't like.
Grains attract crows and grackles.
Seed that doesn't appeal is often tossed off the feeder. Grains Oats, buckwheat, and cracked corn are often part of commercial mixtures. I find they attract larger birds, such as crows, that push the smaller birds aside. Cracked corn sprinkled on the ground distracts them from the feeders. Unless you have a homegrown supply, peanuts are the most economical nuts to offer.