Dell 27 4K UHD Monitor - S2721QS for 340.00. Seems like a good deal. YMMV. https://www.dell.com/en-us/member/shop/accessories/apd/210-AXLG No affiliation here, just saw the deal.
Check out this web site, every week day after 5 pm or so they post a list of sales in their ET Deals: https://www.extremetech.com/tag/et-deals , I got my Dell Monitor that way and it came with a $100. Dell Gift Card as icing on the cake. which ended up getting me a new Logitech Trackball and Keyboard.