1989 Score Football cards and the complete set are limited in production and contain some key hall of fame rookie cards. The second most highly sought after one is the 1989 Score Troy Aikman rookie card. This hall of famer books for around $40 in the Beckett price guide. It is the most highly sought after card next to the Barry Sanders rookie card. You can get a near mint to mint ungraded version for $15-$20 or so on Ebay, sometimes a bit less depending on the auction. Graded versions sell for a bit more and are nice to have. You want to make sure that you get an authentic card, there is a notation in the Beckett to beware of counterfeit cards of Aikman and Sanders. Make sure that you buy from a reputable source on Ebay.
If you are not a member of ebay, you can join by clicking a link below. Get a good deal on the rare card! You can find a great deal here and get a rookie card of him in NM-MT condition from 1989 Score for $15 or so. Aikman is a good rookie card to have.