Storeowners have to pay upfront for deliveries of wholesale gasoline to fill station tanks.
But the store's return on investment - usually a profit of 1 or 2 cents per gallon - isn't realized until either the customer pays cash or bankcard companies credit the store's account for debit and credit transactions.
When gas prices go up, retailers have to set aside more cash to make their fuel purchases. This means retailers have less capital to invest in other, more profitable parts of their businesses.
Vineyard said the drop in gas prices means customers may have more money to spend on other items.
"The less money you spend on gas, the more money you have on disposable things," she said.
She said retailers have been making investments in store improvements and expanded product offerings in recent years. Now they hope consumers will be able to take better advantage of them and develop loyal buying habits.
"We've really diversified in the last few years on what we have to offer," Vineyard said. "Hopefully, if people have more money to spend inside, the more likely they are to come back."
Vineyard said Charleston prices might drop to the cheaper levels around the state in the coming days.
Parkersburg retailers are more sensitive to price swings in the Chicago and Great Lakes wholesale markets, Vineyard said. Those prices have plummeted in the past few days, and the decline has had a trickle-down effect throughout the region.
She said retailers with higher prices should start lowering their prices once new deliveries of lower-priced wholesale gas arrive.
"A lot of it depends on transit times and how much fuel you have in the ground," Vineyard said. "It won't take long for it to all catch up."
Prices could stay in this range for some time, too.
Vineyard said the U.S. Energy Information Agency recently updated its forecast.
The agency now predicts U.S. gasoline prices for 2013 will average $3.43 per gallon, down 20 cents from the $3.63 average in 2012.
The agency predicts national gas prices will stay in the $3.30 to $3.40 range through March, before increasing to the mid-$3.50 price range when the summer driving season begins in May.
Contact writer Jared Hunt at jared.h...@dailymail.com or 304-348-5148.