Site selection can be a relatively simple process when selecting a turnkey solution like a collocated space for a disaster recovery site. Alternatively, the process can be terribly difficult when tackling a complex project like building a new data center from the ground up. In either case, you have to decide if you want to handle all the research and work in house or if hiring a consultant is the best approach.
Handling the process internally saves time and money when the site selection process is simple. Hiring a site selection consultant is almost silly when just selecting colocation space. But a consultant is essential for projects that are more complex like buying a new space, converting a space, or building fresh. Outsourcing a complicated site selection process like a nationwide search for site will also save time and money.