Parmandur
Book-Friend
Sometimes gambling is fun. Unlike Blackjack in Vegas, at least you get some cool collectibles and game pieces no matter what.You forgot Bundle and Commander Decks. The safest investment is the Commander Decks because you will know the cost and value before hand, no gambling. Beyond Commander Decks unless you enjoy limited, your better off buying singles off the secondary market, because as I said everything else is gambling.
The Bundle is just 10 draft boosters and some land and some other swag (and three Dungeons, in this case).