I like to keep in mind that I am paying a company to spray pesticides and herbicides when I buy their sprayed product.
Whoever I buy my food from, with the dollars I hand over I am saying "Yes, I agree with how you grow food. Go grow some more! Here's some of my money to do so!"
It's not just concerns my personal health, it's the health implications for the entire population of all animals on the planet that keeps me from buying conventional anything. If I can't afford the organic variety, I'd rather not eat it at all.