So if you used clossalai u could do locally with a reasonable budget 2-3k. Without that it depends on how much u are using it. If you use it a lot you can do a home setup for anywhere from 32-64k. The cheapest you can do an 8 gpu nvidia home server is around 12k and you need 4x to do 500 Gb vram. (32k new 16gb ram gpu ~1k each ) with used everything maybe you could get to 8k. ( this assumes you could do 16 servers with 4 gpu each all used ) https://alpa.ai/tutorials/opt_serving.html

TLDR largest opt is going to require some model pipelining to keep costs down