'Bullseye' literally means to hit the direct target. It can also mean to do something very correctly. This advert is saying Bullseye because you have come to the right place where they can help you reach your target score. Another example: She hit the bullseye on the dartboard. It was a bullseye decision. "Bullseye!" he shouted after scoring a goal.

I would actually find this a bit strange. Just cut "bull's eye" and it would be fine. I'd use it more as an answer to say someone was exactly right.