eBay and Newegg currently have the VIZIO E50x-E1 on sale for just $279. That is about $200 off of its regular retail price, and it is also the lowest price ever for a refurbished model. These are refurbished models, but do have warranties available.
The VIZIO E50x-E1 is a 50-inch 4K TV that has SmartCast built-in. What that means is that it does have Chromecast inside, allowing you to easily Cast content from your smartphone over to your TV, without needing to buy another Chromecast and using one of the very precious HDMI ports on your TV. There are four HDMI ports, a composite, a component, and an ethernet port included along with 2 USB ports for good measure. This TV also has two 10W speakers inside and use DTS Studio Sound to offer up some pretty great sound. While it's not Dolby Atmos, it will keep most people satisfied.
Both eBay and Newegg offer up free shipping on this TV and neither of which collect taxes. So you're looking at $279 out the door. Now this refurbished TV is rated as an A, for condition, but it's still a good idea to pick up an extended warranty, just in case something does happen to the TV, you'll still be covered.