I have over 1800 baseball cards from 1970-1980s are they worth a lot?

Depends on the cards, many will be worth about 10 cents each, you may have some worth 100's, and maybe one or two in the 1000's

Or they could all be 10 cents each, if you even find someone who will buy them

So much depends on what card, who made the card and the condition of the cards.