What is 1989 upper deck card set worth?

Answer 1

Not much. 1989 is well after the "collector" market was in full swing, so lots of people bought complete sets and put them away in the expectation that they'd someday be worth what complete sets of, say, 1970 Topps cards were then worth.

A rough estimate for a mint condition set would be around $50, most of which comes from the Ken Griffey Jr. rookie card.