8 pack of Amazon Basic 9 volt D-cell Alkaline batteries – $8.67 w/subscription – Free S&H w/ Prime or orders $25+

Great price for Alkaline 9 volt D-cell batteries. Normal price is $10.60 but selecting subscribe and save you get a 5% and a 20% discount = $8.97 including tax. Just cancel the subscribe and save after you receive the batteries.
https://www.amazon.com/AmazonBasi…rch&sr=8-5