Rarity Check: Sea Hawk (Zellers)

[Mindfield]

I was doing some PC troubleshooting for a coworker today, and in partial thanks (and through conversation about collecting) he mentioned he had an old Atari system. So he rummages through a filing cabinet and yanks out a 2600 Jr with 3 cartriges: Donkey Kong (red label), Combat (text label) and this: Sea Hawk (Zellers) (cart only) in excellent condition -- only a small crease on the lower right side of the front label.

 

How rare is this thing? I know Zellers carts were Canadian and probably hard to get in the US, but the Rarity Guide doesn't list this version of Sea Hawk, only the Panda and Froggo versions. The site I linked to rates it at 5.85 (Extremely Rare) but is that accurate?