Hardware needs for most of our solutions, whether a database server or a light duty webserver, can be met using comparatively inexpensive hardware/software combinations. For single purpose server solutions such as a database or webserver a Linux OS based solution works. If you want to introduce file sharing or user management into your organization then a Mac OS X based solution works well. Since Linux OS is free and open source you don't pay for it. You do need to purchase hardware and for that there are two options. First, we can build you a system, and, second, we can purchase a machine from a major manufacturer. The benefit of a major brand is that they come with warrantees. A Mac OS X Server based solution is nearly free of cost. Apple has stopped charging for it. What you have to do is buy the desktop software and from there you can add on the server software at no additional cost. We prefer these two hardware/OS combos as they are stable, efficient, and have advantageous licensing costs compared to Windows technology.
To give some sense of scale for the above suggested solutions let's say they work for the small to medium size organization with up to 200 users. For a webserver you may increase that number to 1000 or more users. Both depend on the specifics of the solution and at some point hosting these solutions "in the cloud" must be considered.