I had a Look at cplicense.net and from what I heard from 3rd parties they can be trusted BUT they do not offer extensions.
cplicenses.net Rates:
Web Admin $ 8.7
Web Pro: $ 13.5
Web Host: $ 23.5
Have a Look at ip-projects.de: (
Plesk Licenses - IP Projects)
Web Admin: € 8,90
Web Pro: € 12,90
Web Host: € 22,90
All for fees for VPS. I personally use ip-projects.de since a Long time as their Support is pretty good.