• Enable price indexing on the req_itemType table
• Create a workflow for each bracket of variance you want to re-direct
• Create the brackets in the Req_Item_Type_PriceIndexing table linking it to the relevant workflow. The workflow will be an addition to existing workflow. Meaing the workflow will be inserted into the existing one and not only appending

Notes If the standard price on the inventory master is 0 then no price indexing is calculated and the logic is ignored. If there's no record in the Req_Item_Type_PriceIndexing table for the relevent variance then noting will happen. The new workflow is checked when the person who's forced to select the vendor is processed