Selling Magic cards was my first business! My friend and I took all of our Bar Mitzvah money, drive two hours across town to the “bad” part of town, and bought two boxes with 50 cases each. It worked out to $1.25 per pack.
Then we sold the packs individually out of my trunk at places where nerds hung out for $2.50 each (retail was $3, but we had no overhead because dad paid for the car and gas!).
We sold one box worth and opened the other box, so we broke even but got a bunch of rare cards.
Including multiple sets of multilands. I put two full sets into sleeves and packed them away, and then made a five color deck with all rares and multilands.
I didn't make a business of MTG until the end of high school and first part of college, ~1999.
eBay was new then, and an older friend showed me the prices on eBay and told me how to make money buying/selling. Since I was traveling to go to the Pro Tour/etc, I had a lot of opportunity to buy cards to sell... mostly bad cards from good players that sold well to casual players (think big dragons).
It's been so long I can't remember. Most of my cards came from Revised because that is what we sold and unboxed, so I basically had all the most powerful things from there like the Serra Angel, Shivon Dragon, Wheel of Fortune, Mana Vault, Copy Artifact, Demonic Tutor, Vesuvan Doppelganger, Winter Orb, Armageddon, Mana Flare, Will O' the Wisp, and all the multilands, which is what made a five color deck possible.
Then I had a few strong creatures with trample damage, and a few Limited and Beta cards that I had traded for like a Time Walk and Ancestral Recall, and at least one Mox.
But I never had a Black Lotus, although I almost got one once.
You might enjoy watching some Old School format MTG on youtube, I got into that for a while. It’s neat to see a modern take on the game as it was in 1994, and people play with spectacular old cards.
Then we sold the packs individually out of my trunk at places where nerds hung out for $2.50 each (retail was $3, but we had no overhead because dad paid for the car and gas!).
We sold one box worth and opened the other box, so we broke even but got a bunch of rare cards.
Including multiple sets of multilands. I put two full sets into sleeves and packed them away, and then made a five color deck with all rares and multilands.
My buddy and I were basically unbeatable.