Another solution would be to simply search the table three times

CopySELECT 
COALESCE( (SELECT row1 FROM table WHERE id=my_id), NULL),
COALESCE( (SELECT row2 FROM table WHERE id=my_id), NULL),
COALESCE( (SELECT row3 FROM table WHERE id=my_id), NULL)

The COALESCE() function accepts more than two parameters. For example, the following is valid syntax:

SELECT COALESCE(Expression1, Expression2, Expression3, Expression4, Etc)

Not sure what you're actually stuck on?...if you could provide your table definitions, some sample data, and example expected output, it may make your goal more clear.

For example, you can concatenate two subqueries together in the same expression of the COALESCE() clause, if your goal is to show the price with the productDescrip together, like so:

SELECT 
    productSerial, 
    productName,
    COALESCE
    (
        (
            SELECT TOP 1 price
            FROM productPrice pp
            WHERE pp.id = wi.id
            ORDER BY pp.date
        ),   
        CONCAT
        (
            (
                SELECT TOP 1 price
                FROM productPriceEast ppe
                WHERE ppe.id = wi.id
                ORDER BY ppe.date
            ),
            ' ',
            (
                SELECT TOP 1 productDescrip
                FROM productPriceEast ppe
                WHERE ppe.id = wi.id
                ORDER BY ppe.date
            )
        )
    ) as baseprice
    FROM warehouseItems wi

Assuming your ORDER BY ppe.date clause is deterministic for a given ppe.id.

Or even simpler, CONCAT() the two fields inside the original subquery expression like so:

SELECT 
    productSerial, 
    productName,
    COALESCE
    (
        (
            SELECT TOP 1 price
            FROM productPrice pp
            WHERE pp.id = wi.id
            ORDER BY pp.date
        ),   
        (
            SELECT TOP 1 CONCAT(price, ' ', productDescrip) AS priceAndProductDescrip
            FROM productPriceEast ppe
            WHERE ppe.id = wi.id
            ORDER BY ppe.date
        )
    ) as baseprice
    FROM warehouseItems wi