Here's our Free VMS Software Directory that should help you on the cost side.
The 'best' VMSes tend to be the most expensive but that still depends what you need (i.e., do you really need access control integration, server redundancy, network video walls, etc.).
If you are fine with basic / modest feature sets, the free VMS list above should help.
A couple of qualifying questions could make your request for information a little bit more fruitful.
IE: How many cameras are you planning on implementing? 10? 50? 500?
Is it important that the client work in multiple operating system environments or do you only use Windows at present?
Are you trying to do complex things like Active Directory integration or just want basic recording whether continuous or on motion?
John's link will help you but some more detail on what your plans are will help you get feedback from other members.