"What we see depends mainly on what we look for."
― John Lubbock
With so much information on magic prices out there, it can be easy to get lost. Knowing what to look for is something that a lot of people have a hard time with. The price of a magic card is a very strange thing. Some people see it at the price that their local store sells it for. Others see cards at the amount of money of cash they can get out of it. Then there is everything in between. The way you see the cards can make or break the bank. There are a lot of factors to consider, so let's start from the beginning.
At some point, you have to acknowledge that you don't own a large MTG store. Just because a major store is selling a card for $5.99, that doesn't mean that it is worth $5.99 to you. As a player/trader/collector, you have to understand where you fit into the economy of Magic cards.
To the typical player, the real value is what a store has listed on their buy list. All stores are different, so the more information you have the better. These numbers don't always go up and down at 60% of the sell price.
Cards that move slow and are going down usually have a low percentage of the price tag as the buy price, while cards that are hard to keep in stock or are going up will usually have a very high percentage of the price tag as the buy price.
To some others, the value could be what they can get from selling the cards online. It is work and you have to consider your time, but in many cases, it is well worth the time and effort to increase the returns on the cards.
To the rest of players, they may not have a plan for getting cash out of their cards, but it's more about just the trading power of the cards that they own and being able to play the decks they want. This trading power is just a reflection of the price, and it matters just as much, no matter if you intend on selling the cards or sitting on them.
In all three cases, and combinations of the three, the bottom line is that you should have an idea of what you are going to do with your cards after you get them, which brings me to my next point:
Have a Plan
Have some idea of what you want to do with your cards. It doesn't have to be written out and formal, it just needs to be an idea of what you have and where all of it is going. Card prices change over time, so having a plan can help you make the most of your cards, instead of being left holding the bag... of Hellriders.
So, before you buy or trade for a card, give it a thought on what you are going to do with this card. Are you just buying because it’s cheaper than other places? I used to buy cards that I thought was underpriced to add to my trade binder. It took awhile to learn that these cards were either very slow movers or just cards that are falling in price, not that I got a great deal on a mispriced card.
The plans that you want to stick to are all along the lines of buy low and sell high. If you are trading, you will want to trade your cards that are part of the awesome new deck for cards that may go up later or cards that
have more stable prices, like cards that are good in Modern, Legacy or Commander.
If you are buying and selling the cards, there are a few more steps and costs involved (shipping and time), but the basics are the same: Buy cards that you think will rise, and sell cards that are at their peak. This can be flipping cards that just got unbanned or this can be a long term investment.
Trends are like shortcuts. It’s a bunch of statistics on what other cards have done to give us an idea of what something may do in the future. They don’t always reflect what is going to happen, but in a lot of cases, they do. The more you know about what has happened, the easier it will be to predict what will happen.
New cards: 90% of the new set will drop after 1 month. It's easy to buy into the hype and think that you might actually hit it big. Just make sure you know what you are doing. I have only preordered 1 playset of cards in my life. It was a set of Baneslayer Angels. I picked them up for $15 each and sold them 6 months later for $60 each. This means that I have missed out on a lot of money, but there is a lot of money that I could have lost, but didn't by not buying into something that I didn't fully understand.
The reason the new cards will be pretty low a month after they come out because most people don't want to buy cards from the set that they are currently winning packs of and drafting. If they have 2, they don't want to buy a 3rd and 4th, then open a 5th and have an extras and less money for it. They will usually just wait until the next set comes out. Meanwhile, there are people that have opened a 5th and don't want it. Those extras are the cards you should be looking to pick up.
Rotating cards: Most of the cards that are rotating out of standard often go down in price; even if they are played in other formats. It's easy to see profit in that. Just don't get bit. These cards don't go down for long and often will come back even higher. In some cases, there is room to make money, but others have such small margins that listing fees and shipping will eat all of your profits. If the card is good in older formats, it's not a bad idea to hold onto it. Even though the Legendary Eldrazi went down as they left standard, the price bounced back higher than then they were in standard.
This is only the case for a small group of the cards rotating out of standard, the rest are going down in flames. These are your $1 - $3 cards that are in standard. They will be the cards that you could have traded for good cards, but instead they sat in your binder for 4 years then got sold to a dealer by the pound. The more of these cards you can trade away for stable cards, the better off your collection/wallet will be.
Non-rotating formats: With the rise of modern and the reprintable nature of the cards, this will be an interesting one. Much will be learned, but the price will probably fall with each reprint and rise until the next reprint or the card if outclassed. MMA being a pretty big exception because there were so many new modern players that got into the format after the release.
This isn't going to be legacy. The originals of cards like Tarmogoyf and Vendilion Clique aren't much different price than the reprints. So, the plan of buy it and throw it in the closet for 10 years isn't as good as it was for legacy cards. This will be a format that financially rewards the people who have a good understanding of the ebb and flow of prices a lot more than the hoarders.
Magic is many different games in one with a lot of forces on the market. There are seemingly endless amounts of facts and opinions at your fingertips. Just start from the beginning and stick to the basics. Hopefully this has opened a few eyes and get people moving in the right direction. If you have any questions, just ask.