How to create a Price Index (see image)

Here is one way. Set up the model with a dimension table (recommended) and an independent table for product (you will be using this independent product table for the slicer). The model looks like this:

 Set up the table visual using the field from the Product table; the slicer from the 'Select Product' table.

Then these measures:

Price = 
DIVIDE(SUM(fTable[Venta]), SUM(fTable[Unidades]))

and

Index =
VAR _Selected =
    CALCULATE (
        [Price],
        FILTER (
            ALL ( 'Product Table' ),
            'Product Table'[dProducto] = SELECTEDVALUE ( 'Select Product'[Producto Sel] )
        )
    )
RETURN
    DIVIDE ( [Price], _Selected )

and you will get

sample pbix file attached

WOW Excellent!!!

Rock Star!