Buying vintage cards for resale can be a profitable proposition if one knows what to look for. There are many different angles to take if making money buying and selling cards is your goal. Obviously it is a great situation when you can buy a card for less than it is worth and set it for a quick profit. Flipping is a term you will hear tossed around by those who make a habit of it.
The key to making money buying and selling sports cards is to use the grading services. Typically dealers and most collectors only have cards of star players sent for grading. That means you can often find top condition cards of many common players and small stars in raw ungraded form. The value of these cards can be increased greatly when graded. Some very advanced collectors with large amounts of money try to put together sets in the best possible condition and place their sets in public view on the grading company Set Registries.
About five years ago I met a dealer at a show who was selling a large amount of mint 1968 and 1969 Topps commons for $1 each. I picked out one hundred cards that were perfectly centered and paid for them. My plan was to check the Professional Sports Authenticator Population Report and send the rare ones for grading. PSA compiles a population report that tells all of the members just how many of each individual card have achieved each grade rank. Most of the cards I purchased were very common and I resold them on eBay for basically what I paid for them. Two, however, were quite rare. The 1968 Bob Veale and 1969 Billy Martin cards each had a population of fewer than five issues in PSA 9 or better condition.
I was sure these cards would grade MINT 9 or GEM MINT 10 so I sent them to PSA for grading. Both came back graded PSA 9 along with a bill of $50 for grading cost. I proceeded to put both of them on eBay where they sold for $675 total, a healthy return on my $52 investment. I have since repeated this process with positive results on many occasions. These are many opportunities to do the same throughout the country.
A second way you can use PSA to your advantage is in the area of cards with qualifiers for centering. When you send a card to PSA they deal with centering in two different ways depending on your desires. If you do not want a qualifier they will knock the overall grade of the card down if it is off center typically by two full grades. A card graded PSA 9 MINT (OC) will likely wind up a straight PSA 7 NEAR MINT if you request no qualifiers on your submission form. While some collectors shy away from any kind of qualifiers, the card with the qualifier will often sell for a bit more than the card with the lower numerical grade. You can buy cards and have them graded again, selling them for profit.
If you want to bypass grading companies there are other way to make money buying and selling sports cards. Negotiating skills come into play here. There are two kinds of dealers you will encounter at card shows. Some are full-time dealers or serious part-times who move from show to show and city to city displaying their wares. They are often in no hurry to sell their products because they know eventually they will receive the true value for their cards.
Other dealers, weekend warriors, who set up a table at only a few shows per year or even collectors who have decided to liquidate their hobby to make a major purchase or earn enough to pay off some debts. Talk with dealers as you walk a show and discover those who willing to wheel and deal. When you find one, be prepared to spend a large amount of money. Many dealers are more than willing to negotiate with a buyer who has large amounts of cash he is willing to drop.
The final area you can profit buying vintage cards is eBay. Look for listings with poor pictures or those that end at inconvenient times. I have bought many cards from auctions ending in the middle of the night and sold the exact same cards for profit by ending them on Sunday early evening just because late bidders never materialized.
Not interested in flipping to make money? There are other ways to sell your sports cards outright.