suppose my opportunity cost of time wasted is $x per hour.

The cost of the megabus ticket is:

Direct cost: 25

Opportunity cost: 4.5x

Total cost: 25 + 4.5x

do the same thing for the other ticket, then find the value of x that makes the total cost of both options equal.

PS: i assume he is travelling one way. although if you work it through im pretty sure that wont affect the final answer.