You are looking at building a multipurpose server system and, being in a medical office (if you live in the US at least) will need to have a domain in place for compliance with user account restrictions, control, and logging. This means you need a full Windows Server solution that can manage and run a domain. Now, on the cheap side you can utilize Windows Server 2012 Essentials, which can manage a domain for up to 25 total users. It’s pretty easy to set up and still rather cost effective for a full server OS solution. However, there are some caveats as it does not allow for virtualization. I would recommend investing the little more cost to get the Windows Server 2012 Standard, as it will support domains of any size, supports virtualization through Hyper-V, and you can run up to two virtual machines with that same single license of Server 2012 Standard.
Here’s why I say this. As your office grows, a NAS device is not going to grow with you. It’s a static configuration and build generally which means you’re not going to be able to run additional roles as needed in the future on that same hardware (such as domain controller, print server, etc.) it’s just not built for that. A NAS device, by its very name, is meant for network storage.
Since you will be running your primary medical service off a different system or through an off-site solution, that does eliminate some of the performance needs you may have for your server, and should be able to do what you’re looking at doing with a single physical server. However, I would break up the components into separate virtual machines if possible to help with compartmentalization. What I mean by this is on your physical server I’d run one virtual machine that operates as your domain controller print server, etc. In the future lets say you need to add a program that is run off your server and accessed through your network. I don’t know of many specific software solutions directly utilized in your situation, so in this case I’ll use the example of Dentrix which is commonly used by dentist offices for performing multiple tasks by multiple users across their office simultaneously and runs off of a central server. Instead of installing this software on the same virtual machine as your domain controller, create a new virtual machine to run that specific service and software. In this way, you can make changes to your domain virtual machine without affecting at all the settings or information in your application server virtual machine, and vice versa. There are a lot of reasons for this sort of thing, and I can help with explaining some details if necessary, but will leave that for another discussion for now.
Down to the physical hardware recommendations then: Well, this is kind of tough to say right now. We don’t know exactly what sort of performance you are expecting, the amount of growth you wish to plan for, the level of high availability or fault tolerance, the amount of storage space you need, etc. However, I can tell you that even going with just enough server to run your current needs (not factoring in the ability to accommodate future growth) and standard levels of fault tolerance in the server hardware, you’re going to be looking at much greater than $2,000 for your primary server. But this IS your primary server, the heart of your storage and operation, and you don’t want to skimp on it believe me.
There’s more though that has to be addressed than just the server. Often times I’ve seen medical offices focused on getting their servers upgraded or operating secure and properly and completely neglect their network. You haven’t mentioned what sort of network infrastructure you will be working with either. What sort of firewall, routers, or switches will you been looking at using or are you needing some information on that as well? Do you know the necessary securities and policies