Вам просто нужно Group by
Сгруппировать и проделать некоторые манипуляции по добавлению кавычек и скобок:
let
Source = Excel.CurrentWorkbook(){[Name="Table3"]}[Content],
#"Changed Type" = Table.TransformColumnTypes(Source,{{"Price", type text}, {"Group", Int64.Type}}),
#"Added Custom" = Table.AddColumn(#"Changed Type", "quotPrice", each """" & [Price] & """"),
#"Grouped Rows" = Table.Group(#"Added Custom", {"Group"}, {{"Grouped", each _, type table [Price=text, Group=number, quotPrice=text]}}),
#"Added Custom1" = Table.AddColumn(#"Grouped Rows", "Custom", each Table.Column([Grouped],"quotPrice")),
#"Extracted Values" = Table.TransformColumns(#"Added Custom1", {"Custom", each Text.Combine(List.Transform(_, Text.From), ", "), type text}),
#"Added Custom2" = Table.AddColumn(#"Extracted Values", "Text", each "[" & [Custom] & "]"),
#"Removed Columns" = Table.RemoveColumns(#"Added Custom2",{"Grouped", "Custom"})
in
#"Removed Columns"