score:3
There are really dozens of tour operators that offers tours to the Salt Mines. I would recommend to use collect some flyers and compare the conditions. I personally can recommend the tour that is provided by the Mosquito Hostel in Krakow. They have an agreement with a tour operator that picks you up directly in front of the hostel and then drives you there in a comfortable minibus. After the tour you're picked up at the mines and you can again leave the minibus directly in front of the hostel or in the old town center.
The price was 10 Euro per person including everything, which I personally think is very reasonable. But we got a student discount of 50%, so the normal price is a little bit higher.
I assume that other tour operators have more or less the same offers.