#TimeTravelAuthors 15: Cost of time travel?

Honestly, not much. Financially, you may need to burn a coin. As a mental cost, you need to be careful not to cause a paradox (not because you might succeed, but because time could kill you to prevent it). Thus you may want a plan first.

The reason it's uncommon isn't cost but lack of devices and lack of access to sixth dimensional energy to power them.