I love this question because it helps illustrate just how different fusion is from other energy sources. If it works, a 50 MW Fusion Engine would run for 5-10 years on a single 55 gallon drum of heavy water.

I wouldn't be surprised if that cost is still a drop in the bucket compared to salaries though. How much deuterium is a startup like this likely to go through in a month?

Totally correct. Right now we simply purchase D2 gas in small quantity so the price is relatively high. But even at those prices we'll probably spend on the order of only $100 per month on D2 when we're operating.