2 years ago, we had the final fill on our tank for the winter (about 200 gallons) and it was..... $865! Price per gallon was $4.19.
Here's the kicker... When we bought the house, we had no previous experience with oil heat (none with any heat really since it was our first place outside of a mobile home and that was really cheap.) We were using a tankful every month through the winter (68 on the thermostat) and with the cost being roughly $200 to fill, thought that was normal. After all, my parents were on a budget billing for gas and was paying $200/month all year long.
That summer, we did a lot of work insulating the house, and along with the price going back down to normal levels, now we fill up the tank about twice per the past 2 winters instead of once a month for 5 months.
We were topped off (now on a schedule) around Thanksgiving and it was $2.19 or $2.29 I think.