I know how you can add a markup to a specific item without the customer seeing it, KirkLohry. Let me guide you through this process.

In QuickBooks Online (QBO), you can use the Price Rule feature when creating a new markup for your specific item. But before doing so, let's activate it first from the Gear icon.

Here's how:

Step 1: Turn on the Price Rule

If your Price Rule is already on, skip this step and go to Step 2.

1. Go to the Gear icon at the left navigational panel, then choose Account and Settings.
2. Click the Sales tab, then locate the Products and Services section.
3. Press the Pencil icon, then turn on the price rules feature.
4. Click Save, then Done.

Step 2: Create a Price rule for your product

1. Go to the Gear icon at the left navigational panel, then choose All lists.
2. Under the Product and Services option, click the Price Rules, then press the New Price Rule.
3. Fill out the Rule name field.
4. From the Customer dropdown, you can choose All Customers, Select Individually, or depending on your preference.
5. Click the Price Adjustment method dropdown, then select Percentage, Fixed amount, or Custom price per item.
6. From the dropdown next to the Price Adjustment method, you can pick Increase by or Decrease by.
7. You can also click the Products and Services tab, then enter the Adjusted Price within the item that needs modification.
8. Once done, click Apply Rule.
9. Click Save or Save and Close.

To learn more about the Price Rules, you can refer to this article: Set price rules in QuickBooks Online.

After creating a price rule, you can now create an estimate without worrying if you're customer will see the markup price.

Furthermore, you can group your materials into different categories or services. By doing so, you won't need to select them individually in the future when setting up a new price rule. This will also help you apply the rules quickly. To do this, we can create a category from your lists and then edit your materials or services to add a category.

I'm still here if you want to ask for further details regarding this, KirkLohry. Please let me know in the comment section.