I've recently managed to deploy UltraVNC via Group Policy - cost was free (other than my time!)
I followed a guide by Adam Rush (Deploying UltraVNC within an Active Directory environment using Group Policy - Virtually Impossible)
...But had to carry out some additional steps for firewall exceptions and also to ensure successful Group Policy deployment of the software.
I've documented the process I went through on my Blog:-
Si's Geeky IT Blog: Deploy UltraVNC through Group Policy (Windows Server 2008) to Windows 32 and 64 Bit Clients
Hope this helps!
