Northern Tool offers the Mr. Heater 15,000 BTU Tank-Top Propane Heater, model no. SRC15T, for $22 plus $7.49 for shipping. (Free in-store pickup is also available.) That's the lowest total price we could find by $18. Sales tax is added where applicable. This tank-top heater connects to 5- to 20-lb. cylinders. (Propane tank pictured, but not included.)