Value is indeed subjective. It is really up to the individual to think if paying will equate to what he/she will be getting from the product/service.
In this case, the organizer has packaged the value of 2 runs into 1, and majority of the runners here will not be able to utilize both the runs because the other one is in HK. To the organizer, they have charged what they believe is reasonable for 2 runs to its paying customers so it is up to the customers to decide if they should take the bait, given that they will only utilize the value of 1.
Collectively, there will be a group of people who will think that $80 is not worth what he is getting if he/she had spent it elsewhere. At the same time, there will also be others who believe the value of the 1 run already covers what they are paying (oood race atmosphere, good singlet, good logistics support, free photos etc).
Nobody is right or wrong when it comes to paying value for the same item. As long as the individual is happy.