You can grab a Pack of 60 AA or AAA Batteries today on Woot for $5.99 + $5 shipping.
No more running out batteries and having a beeping fire alarm!!!
That works out to getting a 4 pack for $.73! Since Woot offers flat shipping, you could order 2 sets (1 AAA, 1 AA) and pay a total of $16.98 for 120 batteries, which works out to $.56 for a 4 pack.