I wouldn't call it a "hoax" because organic foods actually do exist, and they do have some benefit. That said, I definitely think the word and label "organic" can be used as a marketing scheme to make people feel better about eating or feeding their children food that has essentially no nutritional value.
Like if you give your child organic juice and Annie's organic graham crackers as a snack, you've essentially fed them foods with very little nutrient value. IMO you'd be better off giving them a banana and a piece of cheese (unpackaged foods), whether it's organic or not.
Organic milk is a complete marketing scheme to make people think they are eating a more healthful diet. In truth, the vast majority of organic milk is "super pasteurized", which means it is boiled for over 10 minutes. That kills off any probiotics in the drink. They only reason companies do this is to make the milk more shelf stable (longer shelf life). IMO, non-organic milk that is rBST-free (bovine growth hormone) and low-temp pasteurized is a better choice, and many brands are rBST now anyway.
As far as pesticides left on veggies and fruits, there is a handy list called "The dirty dozen and the clean fifteen", which lists the fruits and veggies likely to be highest in pesticide residue (apples top the list) and those that are pretty much without pesticide residue even when non-organic (onions top that list).
If you are worried about cost, I would focus on going for organic fruit and veggies off the dirty dozen list, and grass-fed meat if that's an option. I would also avoid preservatives, food dyes, and any chemicals added to food to change texture or taste (artificial flavor or emulsifiers, etc).
Good luck! :)
ETA: As far as whether organic foods "do any good", it's more that the ingestion of chemicals (combined with environmental exposure and genetic predisposition) can increase your rick of serious illness. People who eat whole foods without much preparation (not packaged goods), exercise, and have low stress tend to be healthier later in life. Limiting your exposure to environmental toxins in your diet helps the cause too, but it's just one element of an overall healthy lifestyle.