The DGX-1 is available for a cool $129k: http://www.nvidia.com/object/deep-learning-system.html Correct me if I'm wrong, but I think it's basically a couple hundred NVIDIA 10-series cards strapped together with a full custom NVIDIA software stack.
The P100s have full support for half-precision (i.e. 16 bit) floating point ops. This can mean ~2x improvements in speed and memory usage in comparison to the Pascal TitanX, which is the top "consumer" card. This difference is significant for almost any machine learning workload, which is what a lot of these cards will be used for. NVIDIA gimped half-precision on the consumer cards to drive datacenters, hedge funds,…
After that, it's going to be mostly about memory size and bandwidth.