A new cost often means a new selling price. Stockroom lets you enter prices while you build a purchase order, then offers to update your products at the moments it makes sense - when you save, when you mark the order as ordered, or when you receive. It never changes a price without asking.
Turn on the price columns
On a draft purchase order, open the Columns menu next to the sort control in the items section and switch on Edit prices (and Compare-at, if you use sale pricing). Both are off by default so the editor stays lean - your choice is remembered for next time.
Each line gains price fields. Enter what the product should sell for - Stockroom never invents a price for you.
Push when you save
Save an order where you've entered new prices and Stockroom asks: Update product prices? "You entered new prices on this order. Update your products now, or keep them to confirm when you order or receive."
Update prices pushes them to Shopify right away - even on a draft. Not now keeps them on the order without nagging: you're only asked again if the prices change. Only selling prices push at save; costs wait until you order or receive.
Or when you order or receive
Marking a PO as ordered or receiving it opens the cost and price confirmation - Order & update prices or Receive & update prices. The Update prices card can also suggest new prices that hold today's margin at the new cost; every suggestion is editable before you confirm, and it warns if a new price would reach the compare-at price (the sale badge would stop showing).
For how costs themselves flow from a PO to your products, see Keep your product costs current when you order.
Good to know
Price updates go to your Shopify products, so every sales channel sees them - and the product's price history in Stockroom records the change.
Nothing pushes without the confirmation dialog - declining leaves your products untouched.
The PO shows the pushed prices immediately; Shopify catches up within a few moments.