There are plenty of 3090s on craigslist as well, fairly common to find below 800$, but 4090s are more power efficient and it's easier to manage a single rig wit

There are plenty of 3090s on craigslist as well, fairly common to find below 800$, but 4090s are more power efficient and it's easier to manage a single rig with 7 gpus than trying to network 2 rigs with 14 gpus total. It's also faster for inference without any model change.