How do you plan on making your service's pricing competitive? Amazon's current spot market instances are ~30 cents per hour, which is twenty times cheaper.
I cannot comment on future per node pricing at the moment, but we are currently working on new offerings that should improve both performance (CUDA cores/node) and $/CUDA core metrics.
Our rate for a single K40 at the moment is $6/hr.
(works at Rescale)