While setting price rules in QuickBooks Online (QBO) South Africa is unsupported, I'll share an alternative option you may consider to help manage your pricing needs, Nomvula.

You can create product or service items and set unique prices for each one. Then, when you're invoicing a customer, select the item with the specific cost you've set for them.

Here's how you can generate a new product/service:

1. Go to Sales and select Products & services.
   
   
2. Click New. Then choose Non-inventory or Service.
3. Fill in the necessary fields.
4. Enter an amount in the Sales price/rate field.
   
   
5. Select Save and close.

For more details, check out this article: Add product and service items.

Next, to choose the designated selling price for a customer on an invoice, follow the steps below:

1. Create an invoice for the client.
2. Complete the required fields.
   
   
3. In the PRODUCT/SERVICE column, choose the item with a unique price intended for this customer.
4. Click Save.

Additionally, I've added this resource to help you modify the product/service item types: Change product and service item types.

If you have other questions about managing selling prices in QBO, please don't hesitate to comment below. The Community team is always here to ensure your queries are promptly addressed.