Yes, 3 phase is generally more specialized & expensive.
I'm in the US.
I'm not looking for anything vintage. I would prefer something along the lines of a Siglent SSA3000X-R real time SA, but I'm open to other brands/models. I also like things like the R&S FPH. I want something capable of (included already, or able to upgrade to) 6GHz, but anything above that isn't necessary. Ethernet/SCPI etc. is preferred.
Thanks,
Josh