I'm interested in buying organic, but it's expensive, so I'd like to focus my efforts on those products that require the most pesticides to grow conventionally. The info I've seen on this issue usually refers only to pesticide residue, which I'm not concerned about -- I'm looking to minimize the overall impact on the environment. Basically, I'd like to keep buying less-expensive conventional products for foods that aren't heavily treated, and pay the organic premium only for those foods that account for substantial pesticide use (or other environmental damage) when grown conventionally.

Although these aren't food items, cotton and alfalfa are huge pesticide crops...