Looking for the cheapest? Just stick your thumb out. I make no rules here. Good luck!
If you’re flexible with your flight dates, consider flying standby. Fly out early because you’re not guaranteed a seat until after all the tickets are sold. You may not find a direct flight, but connecting through a major airport usually has more open seats. I have flown standby multiple times with only one experience of getting stuck at an airport for 12 hours; otherwise, it has been smooth sailing.
Look into airline credit cards as well. They tend to require a higher credit score. However, many have lucrative introductory offers. I currently hold two American Airlines credit cards, the second from a promotion about spending just $1 while paying a $100 annual fee to receive 70,000 miles. That should be enough for both of you to fly round trip for free, making $101 a much cheaper option than $500. If you use a credit card responsibly, you can also earn miles over time for your future travels.