I also vote for the gardening angle. It's hits both the ethics and budgets aspects of food. Not only that but it tastes better.
If space is an issue-there's all sorts of options you can try. There's containers, you can try some plants inside, just like other houseplants, and there's even topsy turveys. Just work within what you have. If you only have 5ft of balcony on a top floor apartment, well, maybe all you get is a tomato and a pepper plant or something. It's important to remember that every tomato you eat from your own plant is one less purchased from the store. Also, you can look into community gardens. Some require that you rent space, some require that you trade space for work, some that you trade space for a donation of some of your harvest to a food bank.
If time is an issue-squeeze as much as you can into the time you have. Most everything can be frozen or canned in some way. Grow as much as you can, and freeze everything that you can't eat right away. Also, some plants do well in cool weather, like broccoli and cabbage. Last year, I was pulling the last of my cabbage heads in December, and I am in the midwest, so it had snowed on them a couple of times. And when time do put all the work in is an issue, consider sharing it. My mom and I share our gardens. This year she has cukes, melons, onions and peas, and I have green beans, lettuce, zukes and jalapenos. We both have green peppers and toms and then we combine our harvests to make salsa and canned tomatos that we split, and we share the cukes, zukes, peas, beans, melons and lettuce. And we share the work of weeding among both gardens. Weeding goes a lot faster when there are two of you doing it, even with two gardens.
And, a seperate tip-coupons and strategic shopping. It's very true that there are rarely coupons for fresh and organic. But there's a lot of other stuff, like toiletries that you can save big on, and use that savings for the more expensive food. And, even for stuff that doesn't have coupons, when there's a great sale, stock up and freeze. The key with strategic shopping is to buy when the stuff is at it's cheapest, and preserve it, so that when you need it, you already have it, rather than buying only what you need when you need it. It really is cheaper that way, I have been doing it for a few months and cut my monthly grocery budget by like $200 (I do include toiletries, pet supplies and baby diapers in that cost). As an example, using extra bucks and coupons, I got 4 boxes of tampons and a razor for my dd last night, for free. And tomorrow, I will be getting about 5 packages of baby wipes for free, because Walmart has them clearanced for $1.97 and a coupon came out last week for $2 off on package of wipes, I have 5 of those.
Just start small with whatever you do and work slowly on making little improvements here and there-start your garden with just a few plants, then expand after a few years. Learn to coupon with just one or two key stores or items and work your way from there.
I have a black thumb, but I've always justified it by supporting *other people's* stands at the farmer's market. 
