Vintage Card Valuation

[XZYXZY]

I am looking for a guide that can help me value "vintage" cards.
For example: if a card has a $100 BV and is in "mint" condition
you could say it has a value of $100. What is a card is in "near
mint" condition or less what would the value be? Are there
percentages that can be used for each grade?

Thanks.

 

[dragonslayer913]

If you have a OPG subscription you can look up any card just type in the card information for example 1973 Topps Mike Schmidt-Then click on the card it will show conditional pricing along with graded pricing but you have either have
an Beckett OPG or purchase one...to view the pricing.

 

[XZYXZY]

Thanks.