The answer to your question is not a simple one. There are several sources such as Uptime which provide some general guidelines, but costs will vary depending on Tier Level and Density (initial and ultimate watts/sq ft). Other factors which WILL add a minimum of 5-10% to the project will be design fees, project management fees, permits, connections to utility, etc. In general terms the structure itself will be less than 20% of the overall cost of the project. The M&E will be your most expensive item.