Full CMS Accounts that allow subnetworks?


I Love YTtalk
Hi there,
Assuming one did not create their own CMS Network (I've heard it's near impossible) does anyone know of Networks that will allow applications/requests to open Sub-Networks?

I've considered BentPixels, I won't consider Aficin..

Can anyone lend me a hand here? Thank-you!

EDIT: Assuming I already had ~50 channels that would sign immediately (100k+ views per day in total) and a website/support/channel in place..