A gallon of milk is on track to be cheaper than a gallon of gas on average across the U.S. in September, according to the most recent statistics, the Associated Press reported Tuesday. The average price for a gallon of milk came in at $3.73 nationwide for the month of September. Meanwhile, the average price for a gallon of gasoline in the U.S. was $2.995 as of Saturday, the first time that the national average price for gas fell below $3 per gallon since December 2010, AAA reported.

Meanwhile, a case of one dozen 1.5-liter Evian water bottles sells for $38.99 on Amazon.com. In other words, Evian is going for $8.20 per gallon, nearly three times the price of gasoline. "It's stunning what's happening here," Tom Kloza, chief oil analyst at the Oil Price Information Service, told AP in response to last month's drop of 33 cents per gallon. "I'm a little bit shocked."

The drop, while greater than most analysts predicted, reflects the increasing output of American oil as well as relatively low prices for Middle East oil exports, combined with a slower-than-expect increase in worldwide demand for oil and gasoline. As these factors continue to play out, analysts predict that next year's average gas price could be even cheaper than this year's, which is on track to be the lowest since 2010, according to the AP.

At the same time, domestic dairy consumption is on track to break the all-time record this year, and Class III milk futures -- which influence prices of key dairy products like cheese -- were up more than 25 percent on the year as of last month.

Trisha Pena, of Hermitage, Tennessee, told the AP she recently paid $2.57 per gallon at a local gas station. "I can't remember the last time it cost under $30 to put 10 or 11 gallons in my tank," she said. "A month ago it was in the $3.50 range, and that's where it had been for a very long time."