They’ve significantly increased in price (so much for hardware depreciation…) but you can still get a modded 22GB 2080 ti for $320, or a Mi50 32GB for ~$450 each (used to be $150 a few months ago, alas), or a Mi50 16GB or <$200 but you’d need to stack 4 of them.

There’s also some more exotic configurations but those are probably the simplest options. You won’t get the performance of an RTX Pro 6000 Blackwell of course, and the power consumption will be pretty high so it’s only worth it if you have cheap electricity. But it is possible.