When I first joined, there was only one 10 man group. Myself and Wildflower set up a regular group each at around the same time and both have been successful in GP and DH. Now there are tons of them going!
You should just start your own as there will be enough interest, I am sure.
I found the key to keeping it going was communication via forums and in game mail, and always having one or two people on a back-up list so they could be rotated in when regulars could not make it.
But yeah, the best way if you are super keen is to organise it yourself, because if you wait for other people to do it for you, it may not happen. Or the times may not conincide with when you play.
Good luck, if you need help with boss strats you can ask any of the group leaders, we would be happy to help. (From memory that would be myself, Bentmer, Opaline, Elsimer, Wildflower, Nomadsoul, Rayvana and probaly a few others I have forgotten!)