I'd look into the different formats, they all boil down to the rules for deck building. Standard is kinda lagging right now, but all that stuff is legal in Pioneer and I really like Pioneer. There's also Commander, a format developed by the community.
If you wind up buying packs, set boosters have better stuff than draft boosters.
Also don't get into Modern unless you're willing to pay upwards of $1000 for a deck.