You say that, but the batteries have an expiration date and cost a significant portion of that $2000 which adds up. My very rural hometown (midwest US) is ending it's volunteer ambulance/first responder service in no small part due to these costs. I would argue having an ambulance without a defib is better than no ambulance, but laws don't care.
ZOLL AED uses ten Type 123 Lithium batteries. It's a consumer grade battery commonly see in camera flashlight. Cost around $30 to replace if buy from Amazon. The battery's shelf life is usually in the range of several years, even with the regular AED self-testing.
