Walmart has them in the camping aisle, and sometimes even lodge brand.
Sporting goods stores usually also have them.
Make sure it is not made in China.
Make sure the lid has a lip around the edge to hold the coals from falling off.
Make sure the legs are long enough that a charcoal briquette will lay flat under it without getting crushed.
Make sure the lid fits flat.
Buy a lid lifter, also at Walmart.
You can also buy a lid stand which doubles as a pot stand.
Use the stand to set the lid on and keep it out of the dirt. Also use the stand to set the pot on so it doesn't burn the table while serving.
10 inch dutch ovenLid lifterCharcoal chimney to light coalsLid stand I rarely use this one.
Gloves are nice too.