There are a ton of cases on the market for the Raspberry Pi, some even equipped with cooling fans, heatsinks, and even displays. While most of those can be had for reasonably cheap, those equipped with display or touchscreens can run on the expensive side- costing $20 and up depending on the model. Online retailer Banggood is currently selling a Raspberry Pi case that includes a 3.5-inch TFT LCD touchscreen (480 x 320) and a handy stylus for just $16 (plus shipping).
As far as features go, the case supports Raspberry Pi models 2B, 3B, and 3B+, and sports cutouts for access to all of the board’s ports. It also provides a pair of holes for anchoring the case to a wall if need be. An unusual aspect of the enclosure is it can be used in two ways; with the display, or with a cooling faceplate with fan, which seems like a moot point if you’re purchasing the case for the touchscreen.
In terms of software, Banggood offers downloadable Rasbian images for the Raspberry Pi 3/3 B+ to work with the display; however, you may want to download the images straight from Raspberry Pi website, as those on Banggood may not be updated. It should also be noted that some users have had the wrong orientation for the screen (X and Y were inverted), but Banggood has since uploaded a fix to their GitHub page to rectify the issue, which requires you to edit a display parameter.