How do I apply a pricebook / pricelist when I create purchase order using the Inventory API?

How do I apply a pricebook / pricelist when I create purchase order using the Inventory API?


When I add pricebook_id to the purchase order JSON request, I see the correct pricebook associated with the purchase order but the prices are incorrect. 

Do I have to look up the prices manually and apply them to each item? I should just be able to apply a pricelist to a purchase order and not have to deal with pricing.