I'm a bad consumer cuz I hate buying new stuff. I'd rather shop garage sales than the mall. If possible, I try to repurpose stuff before it goes in the trash. If a friend is moving, they probably have some junky outdoor stuff (like planters!) they aren't planning on taking with them.
Here are some examples:
egg cartons - great for starting seeds and rooting houseplant offshoots. I'll also take an empty one to the farmers market and they can fill it up with eggs instead of giving me a new carton. non garden related, but I find the nice plastic cartons the organic eggs come in make a nice organizer for my earrings.
gallon/quart jugs, from water, milk, juice, etc - cut the top 6 inches off, cut some holes in the bottom, and you've got a repurposed planter! works great with the bottoms of 2 liter soda bottles too.
large metal coffee canisters - works great for rising bread in, and you can bake the bread right in it. and neato - round bread slices!
broken terra cotta pots - big huge chip out of the top? flip it over, put it in a wet shady area of your yard. Makes a great toad home, and toads are just plain awesome.
How do you repurpose stuff that would normally be destined for the garbage?