This here is Steve, and hes going to be joining you every day for well, probably as long as this games around! I feel comfortable opening with a joke because almost every Magic player already knows this guy
The only way to get it for under $15 is to buy copies that aren't actually legal to use anywhere
Collector boosters - packs of 15 random cards including 4-5 guaranteed Rares and Mythic Rares, plus special art cards
Open the Armory is a nice tutor for Equipment decks, and one you can play in Commander without taking up your Game Changer slots
The heavy artifact focus allows you to take advantage of synergistic effects like affinity, improvise, and metalcraft, each of which makes at least one appearance in the deck
For example, while it's in your graveyard, Ondu Knotmaster is a white and black creature card whose mana value is 4