Is it best to buy a train set or each part on its own?

When it comes to value for money the complete train set has to be the way to go.

With a typical train set, you will get: a controller, a locomotive, coaches or wagons depending on which set you go for and enough track to create a fair-sized oval.

The engine on its own could cost as much as the complete set, so you are getting the controller and track for free basically.

This is the best way to start your layout if you have nothing and with the money that you are saving you can look at extending your new layout.