Hongkong-Saipan Route. This route is the cheapest way. If you happen to be exploring Hongkong, then Saipan is just 5 hours away.
For Filipinos though, we need to have a US visa when we enter Saipan. You can book a flight at Hongkong Express Airlines (Hongkongexpress.com). The cheapest deal you can get is USD 50-99 and if you’re lucky enough, business class.
If you plan having this route, just travel light. Check in at least 2 hours before your flight. After checking in, you have to find your boarding gate. Hongkong airport is frigging huge. In your boarding pass, you can see your gate number. Follow the signs and directions where to go. A short train ride might be needed.
Guam-Saipan Route. Guam is a 3 hour flight going to Saipan. This route is best and the most hassle-free way getting to Saipan. US visa is needed though. The airfare should cost around USD 200-US 250.