Replying to Does this sound about right? Experienced metal rail building input appreciated

I am trying to get one of my parent's friends to help me build a metal rail. I gave him the plans which basically shows a 20 foot rail built out of 1" by 3" steel tubing for the sliding surface, 2" square tubing for the supports, and it is drawn to sit 4.5 feet high. he gave me a price of $150 for the metal. does this sound like its about the right price or a bit steep. any input would be helpful. thanks