Another commenter answered succinctly, but for the next time a side project can be evaluated for viability by also calculating estimates for fixed and marginal costs & doing more competitor research. Has always helped me.
I will do such research in more detail in the future.
Back of the napkin calculation results in 0.5 USD / h for an instance with a GTX1080 - compared with an equally GPU performant EC2 instance g3.8xlarge clocking in on about 2.28 USD / h.