I found an easy way to make charcoal assuming you have ready access to wood and like to cook out.
I was grilling out yesterday and had found some wood from a tree at our church. I decided to see what would happen and when the food was done I threw it in the grill.
I use a small Webber which is important because it needs to seal. I let the wood burn and when the flames died down I knew that it was mostly done off gassing. I put the lid on and sealed it up. Then I let it cool.
This was pretty dry wood logs about the size of your fist. I wouldn't go any bigger. Greener wood would take longer.
I live in the city so wood is a little hard to come by. I do see palates in alleys sometimes, I might experiment with that.
Lump Charcoal is $24 a bag in my area. Assuming that you find the wood, this is a simple method to never run out of charcoal. You can actually make more than you use and get ahead.