For most the switch to organic is a gradual process, predominantly due to the cost. This is where I would like to introduce you to the Dirty Dozen and Clean Fifteen. These are the fruits and vegetables that are the most and least contaminated by pesticides. The list is a great resource that allows consumers to make informed decisions for your health whatever your budget.
The Dirty Dozen (in order of contamination)
Sweet Bell peppers
The Clean Fifteen
Note the majority of the cleaner products have a thick skin so this is another good measure to consider when at the markets.
So in summary, buy where possible the dirty dozen organic. Then if you choose you can be more lenient on the clean fifteen. In the end if budget is an issue fresh fruit and vege is always better than processed foods, it is just important to be able to make such educated decisions where possible.