Latitude?
Jake is obviously well set up - I'm guessing somewhere warmer than me. I have half a dozen raised beds about 3 square metres each - but as we've had a bitterly cold spring here in the British midlands, only the onions sets and a few beetroot are planted out - everything else is in trays and pots in the greenhouse, pending our last frost, though most of it will get planted out over the next couple of weekends.
But we're already eating salad stuff grown in the greenhouse in containers, along with a few perennial garden salads (chives, garlic chives, lovage, fennel, sorrel) which are up and running.
And to answer the Evil Auditor - it's probably not worth the time it takes (or the money it costs) in British weather conditions, but there's no simple way to calculate this empirically. For example, I find that growing veg is an infinitely more rewarding and interesting way of exercising than going to the gym, and paying for membership thereof. And of course it's impossible to put a price on the benefit gained from eating stuff straight out of the ground - it tastes better, and my (probably biased) reading of the science says that many nutrients start to degrade as soon as a plant is lifted, so picking and eating on the same day may well have serious health/nutrition benefits compared to the 3-7 day latency inherent in supermarket shopping.
Of course having animals and grazing land means that you can use the resulting fertiliser to get more value from limited veg growing space - and I wonder if Jake uses the manure from his larger farm to boost the productivity of his urban veg garden. I would certainly grow more in the limited space I have (and use more of my garden for growing) if I had a ready source of good bullshit.
Which is one reason why I read the reg, especially on a Friday...
<ahem>