Our deployment is much smaller than yours! Our upfront hardware cost including carpentry and HVAC was around $80k, our monthly cost in cloud was around $5k/mo and now we pay only about $1k/mo in energy (which includes the existing $500/mo bill from the office). We could reduce this further with solar panels, but we share the tall-ish building with 13 other suites and we couldn't get approval to take up most of the roof.
Holy shit that's more than I expected for your type of business. I'm running a SaaS too with half a million users and a lot of data processing, but my hosting costs are way lower... under $10k/mo
Would love to learn more about your setup. Email me if you're interested in chatting. Email in my profile.