Tell Me About - Selling Baseball Cards

I have about 3500-4000 baseball cards from around 1999 and older, all alphabetized by team and then sub-alphabetized by player's name. They were given to me by my dad's friend... I really hate baseball, I think it's boring. But anyway, I've had these cards for at least 8 years and I'm in need of some money, so I want to sell them. Problem is I don't know the first thing about baseball, baseball cards or selling baseball cards. So what should I do, how should I go about it? I don't want to get gypped into selling them to someone for like 30 bucks.

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