I subscribe to a Norwegian flight deal service that constantly sends out amazing deals — both short European routes and long-haul like Bangkok, Miami, San Francisco and Johannesburg. Each deal shows a % discount vs the normal price, and alerts come in dozens of times per day. I want to build something similar. The goal is to surface truly discounted flights from Norwegian airports by comparing real-time fares against historical averages, then publish the percentage drop (e.g. "-53% vs. typical price"). What I need from you: • How do services like this monitor hundreds of routes constantly — including long-haul — without spending a fortune on API calls? • How do they get the "normal price" to compare against? Do they store historical data themselves or use an API that provides it? • A clear recommendation on which API(s) make the most sense — Amadeus, Skyscanner, Kiwi/Tequila, SerpApi or anything else you've used successfully — and why. • Confirmation that your proposed solution captures low-cost carriers like Ryanair, Norwegian and Wizz Air alongside legacy airlines. • A realistic cost model for a small site just getting traction: expected monthly spend, rate limits and ways to keep costs down while scaling. If you've already solved similar price-tracking or deal-detection challenges, briefly describe that experience. Practical know-how matters more than a lengthy proposal. I already have a working website and database up and running. Looking for the right expert to take it to the next level.