They always showed a kids room with a round little bowl sitting on a desk, inside the bowl was a turtle happily sitting on a rock with a small fake palm tree in the bowl. This is so far from the truth it's not even funny. The equipment you need to keep them alive and healthy can run into a few hundred dollars. The costs and ideas here are not written in stone. This is what I have learned through research and experience.
Tanks There are tanks that are high and tanks that are long.
A long tank is the best kind for a turtle. It gives them enough water to swim in, leaving room for a basking area. The water needs to be high enough for the turtle to be able to be completely covered, yet you also need to have a basking area where they can get out of the water completely. This can get pretty tricky because there is also the filter and rocks to consider, which is covered in their respective areas below. We use a 30 gallon long tank.