To me it is worth zero. I know what you are trying to do, and that is come up with a name that makes sense. After all, people buy food, and the green movement has been going on for many years, so you would think that BuyGreenFood.com would have to be worth something, right?
My answer is that the name is worth zero. You just registered it yesterday, so for 15-20 years 6 billion people had the chance to think this was valuable and register it, but everyone passed. Since the green movement has been alive and well for quite a long time, and nobody has decided to register this name, then that should tell you something right there.
If you are going to register names like this it should be in an area where you have stronger expertise than others, or in an area where you are privy to breaking technological terms before others, or some kind of movement. The key is that you need to be ahead of the curve and have some type of advantage the moment you are registering the name.....some type of insight that others do not have. There are certainly many names unregistered right now that are worth money, and many that are worth a lot of money, but this is not one of them.
It cannot be, and it shouldn't be, that at this point in the domain game someone can register this name and have it be worth anything. Oh, if life were that easy then nobody would wash dishes at restaurants for a living. You have to step up and bring something to the table that separates you from everyone else. Some type of insight, knowledge, or experience is needed to buy anything in this world and hope to sell it for more.
Dig a little deeper and I bet you will come up with better than this, if you feel the urge to come up with fresh registrations.