First value in the matrix

So for each month you want the value that was recorded at the lowest level that has data. Write your DAX accordingly.

Something like 

measure  = FISRTNONBLANKVALUE([levels],sum([prices]))

This is done more easily in the query editor.  To see how it works with your example data, just create a blank query, go to Advanced Editor, and replace the text there with the M code below.

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WSs1L1TW0VNJRUoAAQyM9AwMDJL4hKh8ILDBEzDFEzDBETMEisTrRSmmpSVArkawxRbPWBI1vjMbH7kyQ8bmJRZjGo7mHTOtAxicmYTEeLQDItA7i+kok45GUWJBlBcjIrNI8NCPRjLZE0wqxKjYWAA==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Months = _t, #"1" = _t, #"2" = _t, #"3" = _t, #"4" = _t, #"5" = _t, #"6" = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Months", type text}, {"1", Int64.Type}, {"2", Int64.Type}, {"3", Int64.Type}, {"4", Int64.Type}, {"5", Int64.Type}, {"6", Int64.Type}}),
    #"Unpivoted Other Columns" = Table.UnpivotOtherColumns(#"Changed Type", {"Months"}, "Attribute", "Value"),
    #"Grouped Rows" = Table.Group(#"Unpivoted Other Columns", {"Months"}, {{"AllRows", each _, type table [Months=text, Attribute=text, Value=number]}}),
    #"Added Custom" = Table.AddColumn(#"Grouped Rows", "TopRow", each Table.FirstN([AllRows],1)),
    #"Removed Columns" = Table.RemoveColumns(#"Added Custom",{"AllRows"}),
    #"Expanded TopRow" = Table.ExpandTableColumn(#"Removed Columns", "TopRow", {"Attribute", "Value"}, {"Attribute", "Value"}),
    #"Changed Type1" = Table.TransformColumnTypes(#"Expanded TopRow",{{"Attribute", Int64.Type}, {"Value", Int64.Type}})
in
    #"Changed Type1"

If this works for you, please mark it as the solution.  Kudos are appreciated too.  Please let me know if not.

Regards,

Pat