You can add multiple suppliers for any product in ERPAG.
When you are creating a product (or editing an existing one) just choose the 'multiple supplier' option in the fulfillment line.
Once you've done that, list all the potential suppliers in the 'supplier' line and define the purchase price and landing cost fromeach of those suppliers sides.
Now, when you create a sales order for a product and you do not have sufficient quantity in stock, you will trigger a backordering option and this product will appear in the fulfillment section, under purchasing > fulfillment. When this product appears in the fulfillment list, in the suppliers column you will see a magnifying glass next to the suppliers name.
By clicking on that magnifying glass, you will be able to choose between the listed suppliers for that product. The system will also offer you the view of the price.
Once you choose the wanted supplier, you can proceed with creating the purchase order in only one click, by using the bulk action.