Well, the Query column negates the need for Template columns in such cases, so you can ignore that.
Step by step:
Add a Query column, target it at the same table, and apply the following filters:
– First Name is This row->First Name
– Last Name is This row->Last Name
Now add a Rolllup column, target it at the Query column, and select Sum->Price.
If you don’t see the sum option in the rollup, check and make sure that your Price column is a number type.