I'm building a price comparison application for the US and UK.

The app should allow users to search for a product (for example "iPhone 16 Pro") and compare prices across multiple retailers such as Amazon, Walmart, Target, Best Buy, Costco, and others.

The product data I need includes:

• Product title

• Current price

• Product image

• Description/specifications

• Product URL

• Store name

• Availability (if available)

My current idea is to build my own backend API that stores normalized product data and serves it to my mobile/web app. Instead of integrating with each retailer individually, I'm looking for a reliable external product data provider that aggregates product information from multiple retailers through a single API.

For developers who have built price comparison or shopping applications:

1. Which product data providers have you used in production?

2. Which ones have the best US and UK retailer coverage?

3. How accurate and up-to-date is the pricing data?

4. Are there providers you would avoid?

5. At what point does it make sense to replace a provider with your own scrapers or retailer integrations?

I'm looking for real-world experience rather than marketing recommendations.