I've done this before but can't wrap my head around it again.
I simplified my problem in this pic.
excelclip_zpsikwippvu.png
A4 is my dropdown fro the 2 choices in J and L columns
A9 is a dropdown for the cabinet choices in column H

SO I need to find the drawer price for a b24, depending on the drawer selection in A4.
With ISNA function.

thanks