Is there a way to add the sales order line item amount via formula field in item receipt transaction saved search?

Add this result by Joining the Created From . Amount. You may need to add a Criteria for Created From > Main Line False

The created from record is the purchase order. Since the sales order is not a linking record type to the item receipt, I would think only possibility is to see if can be brought in by a SQL formula

How about doing your saved search starting as PO search and joining the Receiving transaction and also then joining your Created From fields. The PO transaction has a single join you both the SO & IR