There is a really wide range of things that can end up contributing to the kind of value that people would ascribe to any and all baseball cards that they are thinking of purchasing with their hard earned money. The rarity of any given card is going to play a strong role in its eventual value, but once all has been said and is now out of the way there are other things that can matter a lot more such as the quality of the card as well as how much damage might have been done to it over the course of its long lifetime.
One thing that a lot of people don’t seem to realize is that there are certain qualities that can dramatically increase the value of a card that you may be trying to sell. A huge example of this that we can think of is a signature from the player that the card was made to represent. If you sell a Hank Aaron baseball card, it might be worth a decent sum of cash. That said, if the card has Aaron’s signature on it, it will immediately start to be a lot more valuable than might have been the case otherwise going up to $150 in value.
The reason behind this is that signatures are a personalized touch that prove that the card was actually handled by the player whose face is on it. Baseball cards are often bought by crazed fans who want to show their loyalty to a particular team or sport, and signatures are highly desired among such individuals so you would do well to locate cards with signatures or get the ones you have signed.