To make a good trade or sale....Know the BV (Book Value) of your card....
This makes it easier for both parties. This way there is no misunderstanding on the price of the card.
For example.....Tuff Stuff has a free price-guide to look up your cards.
Also, it is a lot easier to make a trade or sale if you want to take an extra step and list the BV on the card.
A little extra steps on price checks keeps everybody happy and helps eliminate the need where we the staff have to settle a dispute. Remember, cards prices go up and down with value. A minute or two checking on prices produces a "Happy Trade or Sale."