RUN_COST="Y"
RUN_SELLING="N"
RUN_RATIO="Z"

for prm in RUN_COST RUN_SELLING RUN_RATIO
do
     echo $prm
     eval VAR=\$$prm
     echo  "$VAR"
done

Ouyput:
RUN_COST
Y
RUN_SELLING
N
RUN_RATIO
Z