I'm not sure about the pricing configuration directly in the Priceable model.
I would do a new `PricingInstance` (better name to be found) model, which stores pricing calculator and configuration. Then in the Priceable model you just select an existing PricingInstance. We may keep an `extraConfiguration` field in this model, that we add to the PricingInstance configuration, for cases when each variant must have a different config.

It will help a lot as well for the UI, as a big use-case is to apply 1 pricing calculator on most products (at least, all variants of one product).