If I were to buy the lowest tier subscription right now, and deicide I wanted the highest tier in a month or so, could I upgrade it and still get the $108.00/year price? (Does that make sense? haha)
No, I don't think so. If you want the per year price, you have to buy the full year of the tier that you want and pay for it upfront. Someone correct me if I'm mistaken!
ETA: What you could do is just subscribe month-to-month on the lowest tier, and then buy a full year of highest tier once you're ready to upgrade.
If you purchase a full year subscription and you decide to upgrade it in the future you can do so on this page. You would be charged the price difference between the two levels - prorated for the time remaining on the subscription.
I hope this helps!
Note: You can't currently upgrade a recurring monthly subscription, but have to cancel and resubscribe at the higher level.