This unit uses a L154 battery which is not available anyplace but with a new unit. So when the batteries go bad you have no place to get replacements except to buy a new unit. Sounds like designed in resales.
Merchant Response:Inside the packaging for this product are the details for battery replacement. The appropriate replacement battery is an L1154 alkaline cell battery or equivalent type battery (i.e., LR44, AG-13, A76, or 357). While we do not sell these batteries, I was able to perform a search for L1154 on the internet and a number of websites selling the battery were available.