Open ticket to vancouver

id like to buy a ticket to vancouver for august but i will likely change the ticket to sometime in decemeber. What airlines allow for this to be done without incurring costs and one that is relatively cheap. One way ticket would be the best.

In your case,the question is not what airline would allow but ,it’s what season you will like to change .

in Taiwan July-August January- february are High seasons.
every Airlines increases fares during this seasons.
When you purchase your ticket at this month then you will get a high season fare.

Well,Cathay Airlines has fare until December.
fare base of NT$29350 plus NT$1470( dep Jul/18-Aug/31)
tax not included.
If you are interested, please email me.
Thank you.