Hi Fahim,
Have you checked a Pier made by Skywatcher? It has the same design you mention and comes with wheals.
I know it's not for G11 but may be you can just add custom made top plate for G11 to it. It is on sale from andrews for $299.
Also there is a company in UK that sells modular pier systems.
http://www.epsilon-telescopes.co.uk/mps.htm
cheers,
Mike