I use a 5000 BTU analog control window unit for a 10'x10' room. It's my second one in 10 years and the price range has usually been around $99-$120 for these basic no frill units.
Double boarded up my window, inside and outside. Also painted the outer board black with a dark screen over everything so it looks like a tinted window unless you're up close next to it. Cut a hole in the boards and mounted the AC in there.
I prefer analog control on the AC so I can set it to high or low with power always on. But temp & power is controlled by a Spartan Series day/night thermostat controller. Set the desired temp on the controller and it will turn on the AC as needed. The controller is also analog but quite accurate and can cost anywhere from $60-$100 depending on the shop.
My cooling being all analog is not fancy or techy at all but it's a very reliable workhorse type set up. But it is getting harder and harder to find analog AC's these days as most have some sort of digital control. There's one on Amazon for $166 but I'd look to walmart, HD, Lowes, for something cheaper if they have it