Baseball/Basketball card collectors

Recently cleaning out an old closet and found a binder of pretty cool basketball cards from late 80's and early 90's. Mainly over 30 or so Michael Jordan cards, a lot of them very sought after according to random websites. My question is, I have absolutely no idea of the value. One in particular I see value in the thousands then at the same time, the same card in the same condition on ebay can be had for $5. I know it's something to do w/ ungraded and graded but am lost with such the delta. Any ideas what I can do to find ballpark value? I'm in the Bay Area (NorCal).

 

Get a trading card magazine...or look at what sold on ebay verse what it's selling for. Most cards that are selling high are graded. Beckett Online Price Guide for all Sports, Non-Sports & Gaming Cards

Do you have this 1986/87 Fleer Jordan rookie card?

 

Unfortunately i don't have that one (wish i did) but I have several others in that supposed bracket.