The problem is that the report doesn't take modifications made by product_cost_incl_bom. So you have to modify mrp/report/price.py and change two things:
line 68 "std_price = product_uom_pool._compute_price(cr, uid, prod.uom_id.id, prod.standard_price, to_uom_id=product_uom.id)" by "std_price = product_uom_pool._compute_price(cr, uid, prod.uom_id.id, prod.cost_price, to_uom_id=product_uom.id)"
line 150 "total_strd = number * product.standard_price" by "total_strd = number * product.cost_price"
The module product_cost_incl_bom also have to be modified (!) by changing line 62 "std_price = sub_product.standard_price" by "std_price = sub_product.cost_price"
Hope this help.