Microsoft have finally announced pricing for Intune. This is $11 per desktop per month, so with the current exchange rates this is about £8. However pricing for the UK has yet to be confirmed.
The expected launch date for Intune is the beginning of next year
The downside is that you will need to upgrade your desktops to Windows 7 Enterprise for it to work, but supposedly the license for Windows 7 is included. If this is true it represents exceptional value.