Just wondering why I cant purchase the trijets like a would a 787.
This was answered in the announcement thread.
New Aircraft
The new aircraft will be available to Pro subscribers only for the time being. If you have a valid Pro subscription you will be able to download all the new aircraft free of charge. This is a way for us to thank you for believing in our simulator and continuing to support its development by subscribing.
Because making these airplanes is a lot of work and money. Paying for a live subscription pays for the ability to make these awesome aircraft!
What do you mean, I didnt see an option too.
Wrong, you need a PRO subscription, you cannot buy individually.
Not at the moment. It is only available to pro members.
Any idea how long it will be?
The developers addressed this in the announcements. They have not publicly discussed when it would be available for non-pro. Anything else is just speculation.