Price the Sales order based on the item number stored in the EFF

Hi All,

Our client has a requirement to get the price on sales order line based on a different item number stored on the line EFF.

Steps:

Create an Order line with Item X and pricing should happen based on the Item Y. Item Y we are storing it in the line EFF.
We will be maintaining the price list for Item X but not Item Y. Please let us know if any one has implemented this solution in your projects or let us know how this can be achieved.