Just because something is vintage or antique doesn't necessarily mean it's worth a lot of money. Some items may even drop in value or change in value from year to year, even if the items were expensive when new. No matter what types of items you collect, these key factors influence the value of your find: rarity, condition and desirability.
Rarity Influences Value
Two items of the same age, condition and subject matter may have two completely different values, depending on rarity. For example, The Beatles' "Yesterday and Today" album was first released with cover art featuring the group wearing butcher jackets, holding an assortment of raw meat and doll parts. This cover was withdrawn after the record label received complaints about it, so another, more conservative cover was released. This album with the "butcher" cover, in good condition, may fetch thousands at auction, while the same album with the more common cover is worth a fraction of that. Likewise, two of the same vintage or antique coins with the same face value may have extremely different values based on stamping errors or the number of coins minted at a particular facility.
Condition Is Key to Value
In many cases, condition is a key factor in the overall value of a vintage or antique collectible. A comic book in pristine condition is more valuable than the same issue in poor condition; likewise, an uncirculated coin is worth more than the same coin with much of the details worn off. If you suspect your item is extremely valuable, such as the first issue of a classic comic book, have it graded by a professional that specializes in the field. This grading counts as a professional opinion for potential buyers and means potentially more dollar value than selling an item based on your opinion of its condition. Grading also eliminates potential disputes between buyer and seller -- what you think of as good condition may be unacceptable to someone else.
Desirability Counts as Well
Even if an item is rare and in good condition, it isn't necessarily worth a lot of money. An old newspaper in good shape but containing no information of historical significance may be of little value to the general public. However, it may be of some minor value to a descendant of someone mentioned on the front page, or to the new owner of a building pictured in the paper. If you haven't heard of anyone seeking out the specific item you have in mind and see no mention of groups or individuals collecting it online, it may have little monetary value.
How to Determine Value
Check online auction sites -- especially closed auctions -- looking up the specific version of your item to get general ideas about its potential value and desirability. If you suspect the item may be extremely valuable, such as a painting by a famous artist, take it to an appraiser that has expertise about such items. An appraiser knows sales trends and current values and may be more accurate in determining your item's value than a local collectibles shop owner would. If you think your item may not be worth the cost of hiring an appraiser, a shop owner specializing in antiques or collectible toys, games or coins may give you a ballpark idea of its value based on their experiences.