1 rack is a recipe for failure, you need to split, even without that consider

  how many SSD's you need.
  power usage for all those SSD's
  inter-site connectivity (need to keep transferring data between the sites otherwise customers are going to be very surprised.
  maintenance and software costs (at the colo level)

All these add up, closer to $50K than some $2K (LOL). The way you guys (below) are talking, this is not some home server that serves personal videos. It runs (some) business operations for thousands of small/medium companies.