Price of Boomerang: 50¥
Boomerang Lessons: Spending a few weeks in the Outback with your Aussie contact
Seeing the look on that troll's face through the Boomereye's camera as it caves in his face: Priceless

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Honestly I don't see much that would necessarily raise the price much from the original 50¥ as it's basically a cheap throwaway camera in a pinch.
Be a good one for submitting for errata though.