You want some if you can but you really don't want to have to pay for it either by having a bad card or a dead card
You still need lands and mana rocks so that you can cast your shrines, and youll want enchantress cards like Satyr Enchanter and Sythis, Harvest's Hand for utility or Sterling Grove for protection
X: Chandra Nalaar deals X damage to target creature
There are incredible sellers, including small businesses, like reputable comic shops and game stores that sell on eBay, so there are reputable sellers you can buy from
I want to point out that there are a lot of spells that are considered "cantrips." These are spells that typically have a small effect on the game and then replace themselves
Decks with cards like The Rack and Ensnaring Bridge are always on the edge of playability, and black-based decks in EDH have plenty of ways to punish people by making them discard