[c-way-dude]

The ironic thing about the ballooning budget for the 2014 Commonwealth Games was the fact that the costs of building a stadium did not go up that much. IIRC, the stadium would have cost $109 million in the initial bid, and $121 million in the final bid. Part of this increase was due to the fact that organizers had decided to go from 15000 temporary seats (for a total of 40000 seats) to 25000 temporary seats (for a total of 50000 seats).
Based on BMO Field ($63 million), and NCAA stadiums mentioned in this thread, I think a suitable stadium could be built for somewhere between $75 and $100 million.