Ignoring duplicates with array formula?

[jetimmins]

Hello,

I'm using an array formula to search through a table referencing one input, screenshots given:

http://i.imgur.com/PiMHo.png - Data
http://i.imgur.com/vuHvP.png - Array Formula

I'd like the formula which currently ignores blank entries to also ignore repeat entries. I've seen FREQUENCY or some 1/SUM functions used but I'm not sure how to build it.

Here's the formula:

=IFERROR(INDEX(GrandTab,SMALL(IF(COUNTIF($C$4,INDEX(GrandTab,,1,1))>0,IF(INDEX(GrandTab,,10,1)<>"",ROW(GrandTab)-MIN(ROW(GrandTab))+1)),ROW(A1)),10),"")

A big thank you for any help!