Steve,
I agree; buying all organic is more expensive. But consider the alternatives. Next time you're in the queue for the checkout, look at the baskets and trollies around you. Many will be filled with processed foods, prepackaged and branded, which cost far more than better-quality DIY food.
Ready-made pizzas, ready-to-cook meals, pre-prepared veg - all of them are hugely more expensive than knocking up some dough, preparing a meal with the basic ingredients or simply topping and tailing your own veg. And that way, you'll know what your family is eating without having to deciper a string of E-numbers.
For too long in the UK nutrition was not taught as it should. As a result, a whole generation of families on low incomes has been buying absolute junk and effectively wasting a large proportion of their weekly budget. And that's to say nothing of the helath implications. Remember the obesity figures last month - which were most worrying in the lowest socio-economic groups.
There are wider considerations, of course - time and the tyranny of the modern work ethic being one of them. But I've had to support a family on an income below benefit level, and we ate like kings - masses of good thick bean soups made with a piece of bacon hock that cost around 50p and plenty of pasta augmented with as much fresh fruit and veg as we could afford. And, though we were poor, we didn't feel poor (but maybe that was down to the home-brew, the home-grown and the elderberry wine!).