Sea Foam/Top End conditioner

[Alero_1986]

Does anyone know where (In Canada) I can find a reasonable product to remove carbon deposit from the top end of my 2.4? I understand that sea foam is a reliable product for the job. So far the only supplier that I have been able to locate that sells this product is NAPA auto parts. They sell a "small bottle" for $15 CAD. I understand that this product is available for around $5 USD or less by many of the american suppliers. The local Chevy dealership sells a spray variation for $6.38(with employee discount). I was informed that they had another variation comparible to sea foam, called 'pour clean', available that has been discontinued. I understand that the spray is not as effective as the other type.
Does anyone have any input or a valid source to purchase a reliable product?
thanks