Not saying Permethrin doesn't work as it is an insecticide but there are many cheaper alternatives, I am sure. We use permethrin as a tick repellent on our outdoor clothing in the spring/early summer.
One alternative to Captain and Imidan is Sevin which can be purchased almost anywhere. One of my buddies who has been growing apple trees for 30+ years swears by it. Not only does it serve as an insecticide, he claims it also thins the fruit so that you don't have to do it manually. I plan to give it a try this year. He says he always get fewer but much bigger apples when using Seven.