Observer as Observable in design patterns

Is it ok to use Observer as Observable for another observer? I mean something like this:

TotalPrice (observator)
    ItemPrice  (observator / observable for TotalPrice)
        ItemCharacteristic1 (observable for ItemPrice)
        ItemCharacteristic2 (observable for ItemPrice)
        ItemCharacteristic3 (observable for ItemPrice)
    ServicePrice  (observator / observable for TotalPrice)
        ServiceCharacteristic1 (observable for ServicePrice)
        ServiceCharacteristic2 (observable for ServicePrice)
        ServiceCharacteristic3 (observable for ServicePrice)

or is there better design pattern for that?