Display only unique values in an array

I am still learning how to really work with arrays. Here's the task:

Column A has a list of "Good" bidders (no "Bad" bidders). Column B has a ranked order of Bidders. Column C is the subject of this post. I am trying, in Column C, to give a ranked order of Good bidders. I have gotten to the point of creating an actual array, but I can't figure out how to display the array (of all unique values) in Column C. Here is what I have (which could be wrong!):

=IF(ISNUMBER(MATCH(C$4:C$43,B$4:B$31,0)),C$4:C$43,"")


How do I make this work? Thanks!

Could you please give some sample that would contain what you have and what you want to get out of this?