If you search the internet for dutch oven recipes, one thing you will find is tables for temperature vs charcoal briquettes. I got a 12 inch dutch oven for my birthday last year and have used it a couple of times since. Each time, everybody loved it. The last time I made a lasagna using a recipe with uncooked noodles. It went over famously.
Mine was from Cabelas and was about $50, but if you have a farm supply store, they usually carry them. Marco, try at a Farm and Fleet. Out here in Boise we have D&B supply that carries a good selection of cast iron.
I use mine on a garbage can lid turned upside down set on some bricks on the ground. That setup would probably work on a campsites grill as well. One thing that makes it easy is a charcoal lighter chimney. Makes it easy to start the charcoal without the chemical lighter fluid.
Enjoy,
Mike