Asset/Invetory Management

I am looking for some recommendations/feedback on Asset Management software. They do not need to be part of an overall endpoint management solution such as SCCM or LANDesk, in fact it is better if they are not.

Basic requirements:
Agentless
Supports OSX, Windows and Linux endpoints
Supports network gear
Supports printers
Reporting and possibly custom reporting

What else I need to know:
Server requirements
DB Requirements
Cost

Thank you in advance!