The exception to this rule is Istanbul. There are plenty of trains from western Europe, Hungary, Yugoslavia, Bulgaria and Turkey, and Moldova, Ukraine and beyond. Between May and September a ferry plies the Black Sea between Constanta and Istanbul. There's no departure tax when leaving Romania, but you have to show your exit card - that's the wee piece of paper they placed in your passport when you entered the country and which you've probably lost by this stage. Unfortunately, the airline has a two-tier pricing system, making flights more expensive for foreigners.
Buses are dead cheap and dead slow.
Buses are generally used only for outlying villages and more rural areas. Train has long been the most popular way of travelling around Romania. Trains provide a frequent service to most cities, towns and larger villages within the country. They are in poor, potholed condition. Similarly, if you want to cycle, the potholed roads makes the going tough for anything less than a robust touring or mountain bike.