My local game store buys Magic collections fairly often. They have a special table in the back where they sort the cards. The good ones go into the case in front, they've got a shelf of binders, and most importantly they've got a penny box.
A given magic block has about 550 cards in it, 1/3rd of which are commons. Commons show up in a booster pack at a ratio of 11 commons to 3 uncommons to one rare or mythic rare. So let's say that the shop has about 3000 cards from Alara block sitting in the back there. Assuming an even distribution they'll get about 12 of each common. Now, they don't need twelve of every single common. they hold on to about ten, but excess cards are dumped into the penny box.
Enter the cheap magic player. I love this game, I love building decks, and of course I don't have the cash to acquire all the cards I want. Or most. Or even many. And honestly, cards like Gravedigger are perfectly fine, if they aren't going to make the tournament decks anytime soon. You can still build a good, fun casual decks. And I do. And thanks to that penny box I've got 47 copies of Terramorphic expanse, waiting for decks. I've spent about $20 buying penny cards.
A couple weekends ago, a friend of mine proposed a LAN party. We'd all bring our computers over and play Diablo II in a networked game until the wee hours of the morning. Ok, it's a good idea, Diablo II still remains one of the best games of all time. I spent significant portions of high school playing the game when I should have been studying, but I got over the game, and in times past I couldn't really work up enough interest to get past halfway through Act I.
I bet you know how this is going to turn out, right?
My necromancer is level 81 now, and doing Magic Find runs in Hell. (Hell is the highest difficulty level. One thing Diablo II did right, they got the style down.) In the game one of the many randomized modifiers you can find on items is "% better chance to find magic items". So you can get items which give you a better shot at getting even better items. It's a cycle, and it's rewarding, and pretty soon you find you can't stop. I got my Blade of Ali Baba and my Goldwrap, but I'm still waiting on my Chance Guards and War Travellers.
The real interesting point about this is the feeling; I can slay my way through the legions of hell with relative boredom, but the minute that Unique Grim Shield drops the adrenalin rushes and I get that cold gambler's thrill while I take my portal in to confirm that it is indeed a Lidless Wall.
I get a remarkably similar feeling when I'm looking through the penny box. Sure, those terramorphics are nice, but every so often I find a card that the store owner undervalued; last time I dug through that box I got a playset of Life and Death, which the internet values at about a quarter, but it's still a much better reanimation spell than they've printed since, well, since about Life and Death. In later times they prefer to print better creatures and worse ways to cheat them into play. I've also found other good stuff in that box, a Zuran Orb and a pair of Animate Dead for example.
And then I think about my brother, Zerg_Rush. He spent more time magic finding in the old days of Diablo II than anyone, and even though he doesn't play much Magic anymore he'd still like you to know he pulled a foil Elspeth Tirell out of the booster packs from Wal-mart.
I usually don't go for casino games; I see the rate of return and decide that I have better games to waste my money on. But apparently the motivation still works on me.