Problem
You want to:
Apply dynamic pricing to all pricebook items for customers without client-specific pricing.
Enable client-specific pricing for specific customers so their pricing reflects a specific labor rate and materials markup.
Make sure customers with client-specific pricing still have access to the full Pricebook with customized pricing applied automatically.
Solution
You can keep Dynamic Pricing for most customers and apply client-specific pricing to selected customers. This setup ensures client-specific pricing customers see a customized labor rate and materials markup, while all other customers still receive dynamic pricing.
Set up dynamic pricing for customers
Go to the navigation bar and click Pricebook.
In the side menu, click Pricing Builder.
Select the categories you want to apply your pricing rule to.
Save the rule.
Keep in mind these rules apply by default to all customers not assigned client-specific pricing rate sheets.
Set up client-specific pricing for specific customers
Note: Account configuration is required to use this feature. Please contact Technical Support for details.
In the Services screen that opens, create a new labor service item for each unique labor rate you plan to offer.
Check the box labeled Labor Service when creating the item.

After creating the items, go to Pricing Builder.

In the Client Specific Pricing screen that opens, click More
and select View/Edit Details to edit an existing rate sheet or create a new rate sheet. 
In the Labor Rate step, add the labor service item and save the rule.

Apply client-specific pricing rate sheets on an invoice or estimate to apply it for that specific customer.