Normal charcoal you can buy in most local markets for about 5000VND a kilo bag. The problem with that is that it can be pretty damp and a pain in the arse to light.
Last time I bbq'd, we ended up buying imported briquettes from Western Canned Foods. They were the fuel soaked ones, so they light very easily. They weren't cheap, but there's enough in the bag to do a few barbecues.