Am I being totally unrealistic? Steel crank value?

Have seen a couple of stock stroke, forged, factory cranks (one supposedly a 340, the other a unturned 318 (did not see a -3 in pics) ) and these people were asking value of them. I responded with $1-150.00 (they were thinking $5-600.00). Am I being unfair in my valuation? Thanks for the replies.