Hi,
If any person from background of Computer knowledge can install SQL server with the little help from MSDN Documents.
Basic installation is as simple as we used to do some other installation.
Here[
^] you can found installation steps.
But configuring SQL Server for best performance for your organization needs some consultant.
The person who is having knowledge of SQL will help you to install SQL server initially. You have not specify why you need to purchase SQL server ?
Hope this information helps you,
Thanks
-Amit Gajjar