I don't have any usable graphic card and CPU is basically useless for anything near serious.

If you want to run bigger models I think 23g of VRAM is a must (rtx3090, 4090, 5090).

Oldest one sucks already. I'm thinking to pair 4090 (if I can get it) with 5070ti for parallel computing (l've seen something similar working).

That's ~$5.5k (whole rig witout periferies)