That's why the big cloud providers charge what they charge - you're basically paying for them to have a huge excess capacity ready and waiting.
If you want to take advantage of the prices of providers like OVH, use colo or dedicated servers from those kind of providers for "base load" for their cost, and tie in cloud resources for traffic spikes or batch jobs.
EDIT: As pointed out elsewhere, though, 200 servers is way above the point where hiring - or contracting with someone - to rack and maintain your own equipment in a colo should be at the very least considered, with some caveats (e.g. location - rack space rental is largely correlated with local land prices, so if you're in a property hotspot dedicated servers maybe remain cost-effective vs. colo facilities within short enough travel up to larger numbers of servers.
