@Groom2Perfection
Do you track the inventory in QBO? If so, I would suggest assigning all of the purchases for the shampoo (or anything else purchased that is split between shop consumables and inventory for sale to customers) to inventory. Then, as you pull inventory to use in the shop, you can make an easy inventory adjustment (New>Inventory Quantity Adjustment) and use "Supplies Expense" as the inventory adjustment account. This will reduce your inventory and book the supplies expense. You can make the adjustment at the time you pull the item(s) from inventory or take a quick inventory periodically and make the adjustment then.
If you don't track inventory, then you can assign all of the purchases to supplies expense. This will book the expense for the product and you will book the income when you sell the item(s).