Extract currency values from text with T-SQL

    CREATE FUNCTION dbo.fnGetAmounts(@str nvarchar(max))
    RETURNS TABLE 
    AS
    RETURN 
    (
    -- generate all possible starting positions ( 1 to len(@str))
    WITH StartingPositions AS
    (
        SELECT 1 AS Position
        UNION ALL
        SELECT Position+1
        FROM StartingPositions
        WHERE Position <= LEN(@str)
    )
   -- generate all possible lengths
    , Lengths AS
    (
     SELECT 1 AS [Length]
        UNION ALL
        SELECT [Length]+1
        FROM Lengths
        WHERE [Length] <= 15
    )
    -- a Cartesian product between StartingPositions and Lengths
    -- if the substring is numeric then get it
    ,PossibleCombinations AS 
    (
     
         SELECT CASE    
                WHEN ISNUMERIC(substring(@str,sp.Position,l.Length)) = 1 
                   THEN substring(@str,sp.Position,l.Length)         
                 ELSE null END as Number
                 ,sp.Position
                 ,l.Length
         FROM StartingPositions sp, Lengths l           
         WHERE sp.Position <= LEN(@str)            
    )
-- get only the numbers that start with Dollar Sign, 
-- group by starting position and take the maximum value 
-- (ie, from $, $2, $20, $200 etc)
    SELECT MAX(convert(money, Number)) as Amount
    FROM PossibleCombinations
    WHERE Number like '$%'
    GROUP BY Position
    )
    
    GO
    
    declare @str nvarchar(max) = 'Used knife set for sale $200.00 or best offer. $20,000.35, $20000.3598, 
    $4,500 Persian rug for sale.
    Today only, $100 rebate.
    Five items for sale: $20 Motorola phone car charger, $150 PS2, $50.00 3 foot high shelf.
    '
    
    SELECT *
    FROM dbo.fnGetAmounts(@str)
    OPTION(MAXRECURSION 32767)