I built a 24 X 16 addon to my barn, the steel was $1700.00 from Menards and that was just 3 sides and a roof. The lumber was $2400.00 and the concrete was $1600.00. I did all the labor myself with friends, I hate to bust your plans but your going to need more cash. Unless you do it in steps. Shop the lumber stores 84 , Carter, and your Home depot, Menards. They will try to beat each others price if you show them in writing a quote.
Good luck
BradC