Dont ever get in a taxi without checking the price which is stuck to the windows. Make sure the meter is running. It is illegal for them to drive without the meter on. Watch out for the RIP OFF taxi's, they look like OK taxis but are fake - the prices are ten times higher.
Dont take a taxi from someone touting at the airport or asking you if you want a taxi. They are part of the con.
Normal taxis are parked immediately outside the airport and bus station, but even some of them will try to con you. Just take out a pen and write down their number. This usually scares them.
My wife paid a 140 Leva for a 12 Leva journey and was threatened with arrest by the corrupt police when she protested. Even Bulgarians get conned.
Warn as many people as you can!!!!
Harry