A few years down the line, all colors will have all of these staple vanillas for most costs plus a few standard-cost draw cards and some others But for now, printing everything in one set would make the set very boring
Since the deck takes a long time to set up, you should attach all other item and support cards to support your setup
While most precons come with the necessary Sol Ring and Arcane Signet, plus a handful of slower mana rocks, they wont hold their own against any deck running Ancient Tomb, Grim Monolith, and many more of the game changers that infrequently come from precons
You can buy gems in Arenas store for actual cash (or cash alternatives), earn them through Draft rewards, or occasionally through events
What is the condition of your card
Here are some of their favorite Advanced Search features: Finding Cards Without Names Search by characteristics instead of names