I bought five 30 count boxes of red scented tea-lights from Pier1 when I stumbled upon them on final clearnace at 90% off (orig. $6 became $0.6, that's $0.02 per candle) with thought that I'd just deal with the given 2-3 hours. FFIL happens to be a candle expert, and we asked him if he can melt some of them to fill the rest to the brim of the tin container in order to extend their burn time. He came up with a much more genius idea:
Uh-huh, not a drop**. Burn time: 5 hours 9 minutes. Cost: $0.04 per candle
* Most tea-lights are filled to the brim which obviously won't work, but Pier1 seem to consistantly carry these above which go on sale all the time for 20+% off. They carry a variety of colors depending on the season.
** I expect some spillage during actual usage, they are contained so it's fine as long as it's not excessive.
Cheap Tip #23: Keep in mind things you need but not necessarily in a hurry. Check out prices for those items at stores you visit anyway. You never know what good deals you'll find!