I've heard of the Black Lotus and Dual Lands. Are there any other really expensive cards in Magic: The Gathering?
Here's one possibility for what you're looking for: a search for all of the cards that TCGPlayer.com sells (directly or as a middleman) for at least $200. At this time, it lists 64 cards in that range.
It would probably be many cards from the very beginning of MTG. It was a special time in MTG. R&D was virtually non existent and there is a lot of cards that would never again see the light of day because of there ridiculous over powered nature. There is also the issue of the reserved list that ensures many of these cards scarcity.
If Star City Games prices are anything to go by here is a rough top ten. For arguments sake I use the Near Mint prices.
10) Alpha Mana Vualt - 800$
9) Alpha Shivan Dragon - 1000$
8) Alpha Birds of Paradise - 1000$
7) Alpha Time Vault - 1500$
6) Alpha Time Twister - 2500$
3) Alpha Time Walk - 4000$
2) Alpha Ancestral Recall - 5000$
1) Alpha Black Lotus - 20 000$
The most expensive magic cards are:
Richard Garfield special occasions- these cards are special editions the Richard Garfield had printed for special occasions in his life. They were really only given to friends and family. They are so rare to even find one for sale is a ridiculous task.
Summer/Edgar magic Dual Lands(or anything summer magic)- these Duals are insanely rare They can easily fetch $10,000 each for the blue ones. Summer magic was a second print run of revised that had much better coloring. however, there were so many print errors in the run that wizards decided not to ship it. Luckily for us, a few cases got released to the public by mistake. Blue hurricane is one card that came from this "set". Basic islands from summer magic have been sold for $500.
The most expensive cards tend to be things that weren't intentionally released. WotC does test printing of cards and many of these have made it outside of the company and can be worth 10s of thousands of dollars.
There was a large test printing of 4th edition done by a different printer, many displays of these were retrieved from a dumpster at WotC and are available on the open market. They are referred to as Summer Magic and are hard to tell apart from the normal printing of the set. ABUgames have a Summer Tropical Island listed for $39,999. This is not a crazy price for these very rare and powerful cards.
Snapcaster Mage from Innistrad, It's not nearly as high as some of the other cards mentioned but it does come up frequently in conversation. I think last I checked the foil was over $100.