Single Card Storage
Soft-sleeves, or "penny-sleeves", are individual soft plastic sleeves about the size of a card (with about 1/16 inch on each side leeway). Usually, these aren't used for protecting valuable cards on their own, but they do keep any of the other holders (with hard surfaces) from scratching the card. These are best used with top-loaders and semi-rigid holders. Some people use soft sleeves with screw downs as well, although they don't work to well with the recessed type. Some people also use soft sleeves for the star cards when storing cards in a cardboard box. Soft sleeves usually cost a penny per sleeve, or $1 for a package of 100.
Top loaders are the most popular method of storing single cards. They are a slim piece of plastic with a slit just narrow enough to fit a single card. They come in a variety of sizes to accommodate the different widths, lengths and thickness of cards. Soft sleeves are often used together with top loaders to minimize the hard plastic scratching the card. Top-loaders usually cost $1 to $2 for a package of 25.
Semi-rigid plastic holders are thin and very light, however they provide less protection than a top-loader as they are less rigid. These are very good for cutting down costs, especially when shipping cards. Many grading companies require semi-rigid holders for card submissions. These come in several different sizes and usually cost $10-$20 for a package of 200.
Snap holders, which "snap" open and closed, are made of plastic and hold a single card. These open by using your fingernail/coin/screwdriver to pry it open by turning a recessed slot on the side. These holders, which can be found for about 50 cents each, are becoming less popular due to the difficulty of opening and closing.
There are many types of screw-down holders, but they all protect the same, regardless of size. These have a rigid, two-piece plastic construction that is secured with a screw. Like snap holders, these are becoming antiquated as a screwdriver is needed to open and close the holder.
Due to the difficulty of screw-down and snap holders, magnetic holders came about in the mid-2000s. Magnetic holders, which hold a single card, come in various sizes. Like screw-down and snap holders, these consist of two pieces of plastic secured together by a small magnet. These holders usually cost $1-$2 each.
Multiple Card Storage
Hinge and deck cases, depending on size, will hold 10 to 400 cards with 35, 50 and 100 being the most common sizes. Both hinge and deck cases are made of plastic; hinge cases have a somewhat delicate hinged-lid while deck cases have a rigid, 2-part construction. Hinge cases usually cost 30-50 cents each, while deck cases, depending on size cost $1 to $3 each. Beware that 150ct hinge cases, the largest hinge case available, are slightly tapered and cards at the bottom of the case often stick inside.
Cardboard boxes made specifically for sports cards are good for storing 100 or more cards. These boxes provide better protection than shoe boxes as they are specifically designed to hold cards. These boxes come in single-row and multi-row varieties. Single-row boxes hold 100, 200, 300, 400, 500, 660 and 800 cards. These boxes usually cost between 50 cents to $1 each. Multi-row boxes hold 1,600 (2-row), 3,000 (3-row) and 3,200 (4-row) cards. Due to their size, the 4-row, 3,200ct boxes are commonly refered to as monster boxes.
Pages and Binders
Three-ring binders and nine-pocket pages are good for cards as well, although if you handle them a lot, taking them in and out of the pockets is a bit of a hassle and the dangers of damage escalate. Make sure you use the pages with no chemicals or preservatives like PVC, as sheets made of these materials might leave a stain on your cards. This is also a good way to store sets as well as special collections of cards (such as all your favorite cards of one player). Currently, two companies make sports card pages, Ultra-Pro and BCW. A 100ct box of pages typically costs $10 to $20.
Storing cards in binders, long-term, has been the subject of many debates in the hobby. Some collectors believe that binders should be stored flat to eliminate the possibility of the pages sagging over time and bending the bottom row of cards. Other collectors believe storing binders upright is safe as long as the pages are snug inside the binder.
When placing a large set into a binder, some collectors use page spacer, a plastic shim that is placed before the first page and after the last page, to minimize the chance that the first or last page get caught between the cover and clasps.
The brand of binder is also the subject of discussion among collectors. Some are fine using less-expensive binders found at large retail stores, while others prefer specialty binders that feature dust protection, slip covers and added protection. Popular higher-end binders include: MJ Roop and Univerture/Unikeep.