Honestly, I see these projects pop up all the time and they always miss the real pain point. Comparing list prices from Amazon JP, Rakuten, and Yahoo Shopping? That's table stakes. The real value isn't in opening fewer tabs - it's in figuring out the actual cost after all the Japanese shopping complexity kicks in.
Price history is the feature that actually keeps people coming back. Without it you're just another affiliate site guessing whether a price is genuinely good or just a fake sale. And the points system across Rakuten and Yahoo? That's a whole other beast. The true cost after points is completely different from the sticker price, yet nobody aggregates that properly. If you're not solving for total landed cost - domestic shipping, proxy fees, international shipping, tax weirdness, coupons, and points - you're not solving the problem.
The original post mentions growing users for the Amazon Creators API. That's a classic build-it-and-they-will-come trap. The audience you listed - expats, collectors, electronics shoppers - they don't need another comparison tool. They need a workflow that tells them: "This is the cheapest way to get this item to your doorstep, including all hidden fees, and here's how that price has trended over time."
Price alerts and coupon tracking matter, sure, but only if the data is reliable. Most "sale" pricing on figures and electronics is fake - a 20% off tag on something that was marked up 30% last week. Without history, you're just amplifying the illusion.
So the real question isn't which stores to include. It's: can you actually calculate the true cost? Because that's the part where every existing site falls flat. Until then, it's just noise.
