The IdeaPad Y900 retailed for $2,400 when notebookcheck did their review on this machine back in September 2016:
https
/www.notebookcheck.net/Lenovo-IdeaPad-Y900-17ISK-Notebook-Review.174445.0.html
The overall verdict was positive, although the Y900 was considered 'late to the game' even at the time of release.
However, while the reviewers did find some drawbacks and odd omissions, compared with similar MSIs and ASUS ROGs, some of the high-points are definitely relevant to your situation. This includes overall build-quality, which is high, and the connectivity options, which are generous. With a DP port and an HDMI 2.0 port you should be able to run two 4K monitors at 60Hz.
The GPU is a bit old by now, but I doubt you'll find a laptop today with similar features at $800.
Happy gaming,
GreyCatz.