Hello, Kai, and welcome to the PCF.
When I started collecting, I said to myself that as far as modern decks, I wouldn't go so crazy trying to find older decks from before I started my collection. It helped to keep my spending a little more in check than it would have been otherwise.
The logic for this is that, especially in today's Kickstarter world, there are so many new decks coming out that there will always be something new, rare, great, etc. and you'll have the chance to get that deck at original retail. Also, getting today's rarities gives you fodder for trading instead of buying when you want to get an older deck - barter deals tend to be more financially beneficial.
Regardless, you enjoy the hobby how you see fit! If you have a question that the Search function can't help you with, just ask - everyone was new at some time and we remember what it's like, so we go easy on the new people and we're pretty friendly in general.