I love the short-term memory by alot of oil burners. One cheap season and they forget not 5 years ago they shelled out 3.50-4.25 a gallon.
Oil is not the only fuel that varies in price. I'd say the same is true for any fuel. Oil and propane seem to be the most varied price, but natural gas, electric, pellets, and firewood have all changed over the years too. The ultimate in low price certainty is having your own woods for firewood. Beyond that there is no certainty on price or even availability. Of course the average over the last few years still show pellets being less expensive than oil/propane but with pellets steadily increasing and who knows what with oil/propane...