[alykins]

You really should move that inline SQL to at least the code behind; preferably to a stored proc... either way the correct syntax (without knowing your database structure that is) would be

SELECT * 
FROM [Products] 
WHERE [Brand] = @Brand 
          AND [Colour] = @Colour 
          AND [Price] BETWEEN @LoNumber AND @HiNumber

so you need to figure out how to split the 'value' into usable numbers. You can pass this to a stored proc easily

CREATE PROC usp_getProducts
     @Brand varchar = null,
     @Colour varchar = null,
     @LoNumber int = null,
     @HiNumber int = null,
AS
SELECT * 
FROM [Products] 
WHERE [Brand] = @Brand 
          AND [Colour] = @Colour 
          AND [Price] BETWEEN @LoNumber AND @HiNumber