I've never thought much about it, but it certianally don't understand how it can be cheaper to buy fresh vegetables than to grow your own.
I currently have a 30 X 150 foot garden. About 1/4 is planted this year (we just moved in and had lots of other chores around the 13 acres to make it look nice again). From this garden, I ran the rototiller through it twice and planted beans, tomatoes, beets and other small crops.
Here is how I figure it:
Rototiller : $350.00
Seeds : 15.00
Fertalizer : 5.00
Misc : ~ 30.00
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Total : $400.00
From garden so far:
Enough lettuce that we haven't bought any spring/summer
Enough radishes that we didn't have to buy any (in fact, gave some away)
Enough eat, pickel and can for the year.
Enough beans to eat, freeze and have for the whole year
Enough tomatoes to enjoy.
To Come:
More tomatoes
More beans
Plenty of cucumbers to pickle for the whole year
Granted, with the rototiller, we aren't making money this year. But think about the fact that the tiller should last 10 years. So if the above holds true, but factor the tiller at $35 dollars, you see i'm around $85 dollars for all that food.
Looking practically at the grocery store prices, I think we're coming out ahead or at least breaking even.
However, the joy my wife and I have from working "in the field" and getting dirty together more than pays off.
So even if it doesn't make it's money back, I would really encourage everyone to have a garden for the reason that Egon said.