Further to the queries on Gen 3 12v batteries, ours has just failed and knowing my local Toyota dealer well I took it there.
They replaced it with a wet Numax Premium sealed battery, £70 all in including washing the car.
When I queried the use of wet, they confirmed that most of the hybrids used to come with with standard wet batteries (vented) even if located inside the car and in fact that our car was fitted as such from new.
Food for thought when considering some of the exorbitant prices being quoted.