This might sound weird, but Novena candles are a great deal.
If you're not familiar with them, they are the religious candles used by Catholics. Primarily Latino Catholics.

They sell them at Walmart, they come in a tall glass container and will burn for days. I'd say at least 30hrs of burn time per jar.

They cost about $2. They do come in plain glass, if you are weirded out by having the "El Sagrado Corazon de Jesus" image on your candles. LOL