Turbulence in the budget airline industry continues to be expected. But for savvy leisure travelers looking for international flights, there are more ups than downs right now.

“It’s the golden age of cheap flights,” said Scott Keyes, who by his estimation has visited 48 countries. He co-founded Scott’s Cheap Flights, a travel site that alerts members when deals pop up.

“We regularly find $300 round-trip flights to Europe, which did not exist five years ago,” Keyes, 32, said.

The Barcelona-based carrier Level, for instance, recently showed flight deals on its website from Newark, N.J., to Paris on select dates in October for $149 one way. Round-trip from Boston to Barcelona featured a promotional price of $350. The 2-year-old, low-cost brand is owned by International Airlines Group and flights are mostly operated by Iberia.

More major airlines are getting in on the act. Scandinavian Airlines (SAS) recently introduced SAS Go fares for travel to Europe. In August, the company ran a sale on round-trip routes from several cities in the United States to Copenhagen, Helsinki, Oslo and Stockholm for under $400. A recent search showed a low-price calendar with dates listing flights in November from Newark to Oslo for $340 round trip, a meal included.

Depending on the airline, return flights are sometimes pricier, an extra $30 or more. Ancillary fees are where it can really add up on no-frills carriers. Concerning luggage, read the fine print on weight restrictions and maximum dimensions. One personal item and a carry-on bag might be included in the price, but in some cases can’t weigh more than 8 kilograms (about 17-1/2 pounds). With economy fares, a checked bag can cost upward of $40 to $60 and double that if you pay at the airport. Also expect charges for seat selection, headsets, pillows, food and water. Print out your boarding passes since there can be a charge for that, too. And don’t expect a refund if you have to cancel your flight.

Another budget-conscious airline greasing the wheels on the runways for overseas flights is JetBlue, which plans in 2021 to usher in multiple daily connections between New York City, Boston and London. More European destinations are likely. A news release in June announced that the company had purchased 13 fuel-efficient Airbus A321XLR aircraft to expand trans-Atlantic options.

Low-cost trans-Pacific travel via AirAsia X is expanding as well. “A bit of a beachhead is forming in Hawaii, and we’ve seen flights from Honolulu to Osaka for $199 round-trip,” said Keyes of Scott’s Cheap Flights. Jetstar, a subsidiary of Qantas, is flying between Honolulu and Sydney for as low as $286 round-trip, he said.

When booking your flight

>> The main money hack is to book as far ahead as possible.

>> Comparison shopping on Kayak, Google Flights, Expedia and other sites tend to yield similar results since they pull from the same data sources.

>> Budget airlines don’t always fly to certain destinations daily, so if you miss your flight, or if it’s canceled, it can be a disaster. Stranded passengers may not be accommodated on allied airlines as they would be on legacy carriers.