If it to be symmetrical height wise you would need to get a 34" ultrawide for it to not have mis-matched monitors, this is not accounting for resolution.
http://www.displaywars.com/27-inch-16x9-vs-34-inch-21x9
The best card you will find in that price range is most likely an rx 470, such as this one: XFX Radeon RX 470 RS Triple X DirectX 12 RX-470P436BM 4GB 256-Bit GDDR5 PCI Express 3.0 CrossFireX Support Video Card from newegg from $170.
However, if you wish to go a little lower, the gtx 1050ti is a good choice, with this ZOTAC GeForce GTX 1050 Ti Mini at $130.
I would suggest your favorite variant of the rx 470, based on reviews or asthetics(if that matters to you.)
Have a great day, and may the masterrace be with you!