In this case you can use Mixed Costing. Here you can have two procurement alternatives defined for this material in t code CK91N and provide mixing ratio for each of them in t code CK94.
In BOM , alternative items are assigned to alternative item group on the general data tab page.
In the production order in the general data tab page.
We can define the alternative item based on priority , strategy and usage probability.
This defines the priority of the item within the alternative item group.
This determines the priority of planned withdrawls of items.
EX Two items are assigned to alternative item group
item A Priority 1
item B Priority 2
The system reads the item A first.
use the strategy to determine how the planned withdrawl is controlled
within the alternative item group.
The strategy should be same for all alternative items within a alternative
If the value 2( 100% check) is defined for the strategy the first material in
the defined priority sequence for which sufficient quantities are available
MRP Plans these alternative material components according to probability
of use.Material requirements for BOM Components are planned according
to usage probability.
The planned withdrawls for the production order are based on the reservation lists.These lists are based on the priority and strategy.