At least around here, getting a septic system designed, permitted, and installed to the satisfaction of the state is generally a five-figure process, or very nearly so. Burying a 55 gallon drum or three and burying them would definitely not cut it. The laws do vary from state to state.
A big holding tank that one has pumped out from time to time might be the least expensive way, certainly with initial cost, as the engineering work is pretty much nonexistent. The ongoing operating costs would probably be higher than a septic system and leach field.