Another thought process to keep the budget down is by adding things like aprons and extra electrical and finishing it out with offices and plumbing till later and at least have shelter and space to work out of.   Of course those things will cost more later.  

thanks for the feedback on those numbers that helps give some insite to OP.   

If your hiring all the electrical, and its bid work, then yes it will be $5.   I did T&M with a really good electrician and it was far less.  I did provide the scissor lift and did all the underground conduit installation though. 
 
very factual that the project WILL end up over budget.