Realistically I think 16GB is the lower limit and you can find those cheap enough still. Then you run llama.cpp to bond your cards and it's off to the races.

24 GB 3090 user here. What is the best model for coding you have used? Qwen3.8 27B?

If you haven't found it yet: ninfer-3090 is worth checking out if you use just one GPU.

I use Qwen 3.8 27b, yeah. I don't really shop around for models a whole lot besides generational jumps, and it doesn't feel like there will be anything too worth switching to until Qwen 4 (hoping they release a similarly sized model, I'm not actually certain they have said they will?)