In general, a rack mounted solution will be more expensive than a distributed setup. The amount of volume for rack mounted equipment is less than that of their desktop counterparts. Additionally, because there are several systems in a single rack, heat dissipation becomes an issue. Furthermore, for a rack mounted setup you would have to add in the costs of whatever input device(s) you decide to go with whether it be a rack mounted KVM, or network connection(s).
There are some benefits such as security. A rack mounted system can easily be locked down to prevent unauthorized hardware changes and limit physical access to the rack. Also, maintenance and support is somewhat easier on a rack because access to all the machines is limited to a single location. Another item to consider is the power requirements. You will need more power to supply a rack rather than single machine, however when it comes to backups, the whole rack can be loaded onto a single UPS which allows for the whole system to remain up in the event of power failure (provided a large enough UPS is used).