Average variance by Item

Should be a simple two step process. 

Create a calculated table of unique ID-Item combinations with their variance

VariancePerIDItem = 
ADDCOLUMNS (
    SUMMARIZE ( 'Table', 'Table'[ID], 'Table'[Item] ),
    "Variance", 
        VAR Prices = 
            CALCULATETABLE (
                VALUES('Table'[Price]),
                ALLEXCEPT('Table', 'Table'[ID], 'Table'[Item])
            )
        RETURN 
            DIVIDE ( MAXX(Prices, [Price]), MINX(Prices, [Price]) ) - 1
)

Then, create a measure that calculates the average of non-zero variances per item:

AverageVariancePerItem = 
AVERAGEX (
    FILTER (
        VariancePerIDItem,
        [Variance] <> 0
            && VariancePerIDItem[Item] = SELECTEDVALUE('Table'[Item])
    ),
    [Variance]
)

When you place Item in your visual and use this [AverageVariancePerItem] measure, you’ll get your expected result.

Please mark this post as solution if it helps you. Appreciate Kudos.