Can you share what your trying to find?
A cpu in my experience is about 20 times slower than a gpu. So that's the price difference that makes a gpu server worth it. I've looked for them a while back, but never tested it on a server.
It is more of a research / curiosity question than trying to find something specific.
I was looking at the difficulty in generating vanity addresses with specific prefixes.
For example (at ~4Mkeys/s)
5 characters case sensitive - starting with a lower case (15,318,045,009 difficulty) - 50% takes about 40 minutes.
6 characters case sensitive - starting with a lower case (888,446,610,539 difficulty) - 50% takes about 36 hours.
So I was simply speculating as to how many Mkeys/s one could generate for a reasonable price. The VPS I use with 6 cores costs 35 euros/month.
Of course, a GPU will cost more - but how many times more? The cheapest GPU (35 cents/h) here (
https://gpurental.com/) costs $250/month. The most expensive ($1.35/hour) costs $920/month. However, I don't have the experience to know what the specifications of the GPU actually mean.
Here is a cheaper example at $99/month (
https://www.gpuserversrental.com/) using 6 x GTX 1050 2GB.
So they are not hugely expensive though the price ranges far more so than for a CPU-based VPS.