Cluj Napoca airport is the nearest and has good Wizzair flights.

Baia Mare has an airport that is closer and has flights from Austria if you are coming in from international connections. A lot of international flights come into Budapest, where you can get the train or bus to Baia Mare. There are also good Bucharest flight connections you can get and then come up to Borsa on the overnight train from Bucharest to Sighetu Marmației.