You mean when they make more to find... there is only at present, the Acer X27 at £2200. Asus will be doing one with that panel supposedly, but expect around the same price. There are not any other 4K G-Sync monitors higher than 60Hz due until next year as far as I'm aware... and nothing has been announced (we can only see panels that are on the way), so there may be delays. You could very easily be sat with an incredibly expensive GPU for months on end with no monitor to really get the most from it (and scant few RTX titles either for that matter). That said, a 3440x1440 ultrawide might be worth considering on the monitor front.
SLI is dead, NVLink is taking its place. They are not the same thing and do not function the same way.