I think we use value to mean cost, and price only for items for sale. But it is not explained clearly, and may not be used consistently. And value=cost does not communicate well.
Both Resource and ResourceType have the field value_per_unit_of_use, but the one on ResourceType is never used, only the one on Resource.
It is used now in two ways:
to compute the value of a use event for passing on to contributors to the Resource that was used,
and now in equipment logging as the price per unit for 3D printer use.
The second one seems clearly to be a price. The first one probably is, too, but is it more ambiguous?
Both Resource and ResourceType have the field value_per_unit, and again,, only the one on Resource is ever used. AgentResourceType has this same field, but also never used.
Resource.value_per_unit is computed in a rollup by adding up the values of all the contributions to making the resource. In other words, it is computed like cost of production.
AgentResourceType.value_per_unit could be used for supplier prices or differential values of work ResourceTypes for different agents.
The field price_per_unit only occurs on ResourceTypes and now is used only (optionally) in value equation claim computations.
Prices are decided by people, not computed by the system.
The field now named "value_per_unit_of_use" should be renamed to "price_per_unit_of_use".
All fields named "value_per_unit" are computed by the system and mean (roughly) cost.
For purchased resources, that means the purchase cost. If more than one purchase, it means the weighted average cost.
For created resources, it means the cost of the inputs of all the processes that went into its creation.
Changes:
Remove "value_per_unit" from ResourceType.
Rename "value_per_unit_of_use" to "price_per_unit_of_use".
When a resource is purchased or created, recompute its value_per_unit as the weighted average of its purchase, production and other costs, using the Resource.roll_up_value() method.
This should use an appropriate value equation if one exists.
I think we use value to mean cost, and price only for items for sale. But it is not explained clearly, and may not be used consistently. And value=cost does not communicate well.