Is it cheaper to fly into one country and out of another?

Yes, often called an 'open-jaw' ticket. Use the 'Multi-city' search function on flight aggregators to compare this against a standard round-trip.

Should I book budget airlines like Spirit or Frontier?

Only if you travel with a small personal item. Once you add a carry-on or checked bag, the price often matches legacy carriers like United or Delta.

Finding Cheap Flights to Central America

To get the best price, set up Google Flights price alerts at least 4 months in advance and aim to fly into hubs like Panama City or San Jose. Use the 'Explore' feature to compare multiple arrival cities, as landing in a different country can save you over $200.

Use the Google Flights Explore Tool. Instead of typing a specific destination, type 'Central America' into the destination box on Google Flights. Set your 'Anytime' dates or flexible month preferences to see a heat map of prices across all major airports in the region.
Monitor for the 'Golden Window'. Set price tracking for your preferred route 3 to 5 months before your travel date. You will get an email notification as soon as the price drops. Do not wait for a 'mistake fare' if you are traveling during peak season (December–April).
Look at Secondary Hubs. Flights to Costa Rica (SJO) or Panama (PTY) are often cheaper due to higher competition. Once there, regional low-cost carriers like Copa Airlines or Volaris can often get you to your final destination in neighboring countries for $80–$150.
Use Incognito Mode (or don't). While the myth that airlines track cookies to hike prices is largely debunked, use a VPN or Incognito window just in case. More importantly, clear your cache before final booking to ensure you aren't seeing outdated pricing from previous searches.

Is it cheaper to fly into one country and out of another?: Yes, often called an 'open-jaw' ticket. Use the 'Multi-city' search function on flight aggregators to compare this against a standard round-trip.
Should I book budget airlines like Spirit or Frontier?: Only if you travel with a small personal item. Once you add a carry-on or checked bag, the price often matches legacy carriers like United or Delta.