Comment by antognini

For a hobbyist, it probably makes sense to just use some GPU instances on AWS. But it doesn't really take that long for it to become cost-effective to buy a GPU. It only takes a couple of months of full-time use before it becomes cost-effective to purchase the GPU. Even if you're building the entire machine from scratch it takes under a year. (At least, that was my estimate when I was building a rig earlier this year.) If you're doing any serious deep learning projects it's pretty easy to have a model training nearly 100% of the time.