just booted up with a coffee and saw your post.
There are several refurbished and/or used highspec notebooks on ebay for 1500 and less.
Just search for Notebooks with a 1080ti. Keep one eye on the video outputs. you want as much as possible.
And the other eye on a present m2 ssd or the possibility to add one. That's it.
It can be practical to use a desktop if you would like to add pcie capture cards, more videocards for more outputs and so on.