I am psyched! I have just come from a quite amazing Window Farm demonstration at the Queens Library (who knew libraries could be so cool?)
Anyway, the cute librarian guy (yes, cute librarian guy) showed us how to, if we are handy, build a hydroponics window garden for (probably) under $50, with re-purposed/upcycled water bottles, plastic tubing (good, now I know where to get plastic tubing for making bracelets!), and a few pet store aquarium supplies. Free instructions here.
So, if I only would put out the minimal cash and foraging for supplies effort, I could have a vertical hydroponics garden in my kitchen window in a few hours or so (actually, the cute librarian guy put it together in under 2 hours, but I suspect he has been practicing).
Imagine, city-dwellers! You could have a whole window worth of organic vegetables at any time of the year! For cheap!