You could use this method, but it is not a good idea for a couple of reasons.
The first being that you are ignoring the power of Relational tables, Queries and Combo boxes.
The second is that the prices are "hard code" by you, which means that you have to keep the code up to date.
So ideally you would have a price field in your table that holds price for the customer.
When the customer is selected in the Combo the price field is included in the combo columns and can be displayed and stored if required or just used in calculations.
I am not sure of your Table Relationships, so I am not sure where the price should be in a current table or a many to many table.
You would then have a simple form for keeping the prices up to date or adding new ones.