Where to procure a no-frills drum bbq grill?
Not sure if any of these are options for you, but Academy Sporting Goods, Wal-Mart and places like Home Depot/Lowe's are worth checking for basic ones. The last one we got for my mom was from Home Depot and even had the off-set fire box. It's nothing fancy, but it's still working three years later. (We did upgrade the cooking grates to some heavier ones.)
Not cheap. Call a local welding shop and tell them what you want. You will have the cost of the drum, angle iron for legs, mesh, and pipes to regulate air flow. Have the welder heat the entire drum to cherry red to cut down on the noxious and toxic residues. Steam cleaning will not work.Now add the cost of welding it all together.
Steel drums are getting pretty scarce. My last one came from a 40 gallon stainless steel flask a tenant left. You might want to look into a 2 to 3 foot diameter section of pipe.