The price at the pump was more than $4 a gallon in Vista, Calif., when Scott Hissem recently embarked on a trip to Texas to celebrate his 40th birthday. When the delivery associate for Amazon.com Inc. arrived in the Lone Star state, he got an unexpected present: Gasoline cost just $2 and change.

The gap has Mr. Hissem considering a move to escape California’s high cost of living.

“It...