We changed the model quite a bit in 2013 when we began focusing on serving the needs of businesses (namely, non-profits).
When we were consumer facing we had a free account with upload limits and an unlimited account for $29/year.
We decided to not differentiate prices based on storage; ours or yours. The pricing page got too complex.
That being said, nearly everything we've done is open source and even when running as a hosted service we decoupled application logic from data storage. That was our goal from the beginning. We went as far as enabling you to switch storage services (i.e move from Dropbox to S3) with a single click.
My mission was to build the technology but in a way non-technical users would understand. I think we accomplished that. Being open source was the underlying prerequisite since it's important if you start on a hosted account you could switch to your own instance or someone else's hosted service.
All that said, I don't think there's a huge market for this in the consumer space today. I hope in time that demand grows because an Internet the way we were envision looks great.
