Hello there, @boojens.
If the inventory that you'd like to add is for a one-time purchase, you can attach the new price on the bill. Please see the screenshot attached for reference:
However, if you wish to add a new price permanently, editing the cost of the item from the Products and Services list will do the trick. This way, the price will be modified and will reflect on your future purchases.
To do that:
- Select Settings ⚙on the toolbar, then choose Products and Services.
- Find the product, service, or bundle you want to change.
- From the Action column drop-down menu, select Edit.
- Enter the new price of the item.

- Select Save and Close.
I'm also adding here some great resources about adjusting inventory quantities and on how FIFO works in QBO in case you need it for your future transactions:
If there's anything else that I can assist you with, let me know. I'd be happy to help. Have a good one!