I am looking to be able to purchase parts and bill them to a customer on an invoice with the mark up. i dont have an inventory just purchase as i diagnose the issue.

You've come to the right place for assistance, rwandr2024. I'll help provide information when billing customers on an invoice with an added markup in QuickBooks Online (QBO).

Since you don't track product quantities to bill a customer and just for purchases, you can set up non-inventory or service items to record products that aren't part of your inventories. To guide you through the detailed process, follow Steps 1 & 2 outlined in this article: Add product and service items in QuickBooks Online.

However, if you want to keep track of inventories and other purchases in your file, you can utilize the billable expense feature available for Plus and Advanced QBO versions.

Once your product items are ready, you'll have the ability to set different markups for different items when you create invoices. You can set up several price rules to be added individually to your non-inventory or service products.

To do this, let's enable this feature from your company's settings. Then, refer to the steps below:

1. From the Gear icon, select Accounts and Settings.
2. On the Sales tab, click Edit in the Products and Services section.
3. Then, select the Turn on prices rules Beta checkmark.
4. Review other settings and click Save then Done.

Once everything looks good, you can set up price rules to add markups on items when invoicing. You can also check the screenshot below for reference.

Moreover, here's how to track and enter customer-paid invoices in your account: Record invoice payments in QuickBooks Online.

I'm always available in this thread if there's anything else you need further assistance with when managing purchases in your file. Stay safe and have a good one!