$34.68 on Amazon
If you have a Raspberry Pi, you clearly already value portability, versatility and quality at a low price and you were looking for a quality, inexpensive touchscreen anyway. You were looking for the 2.8-inch PiTFT Raspberry Pi touchscreen.
It comes fully-featured — 320x240 resolution, 16-bit-pixel color, and resistive touch overlay—and fully-assembled. It’s pre-soldered so all you have to do is snap it onto your Raspberry Pi’s high-speed SPI interface, then install the software from https://learn.adafruit.com/adafruit-pitft-28-inch-resistive-touchscreen-display-raspberry-pi/software-installation.
Once installed, you can use the display as a console or X window port to do what you already do with your Raspberry Pi but better, more portable. You can use your finger or stylus to view images and videos, run applications, and more. You don’t even have to tear apart your overpriced smart phone (that’s a lot of work) or jailbreak it (that would be illegal).
The touchscreen won’t replace your desktop or laptop screen, but it might improve your life. It's perfect for running applications of all sorts. You can listen to your favorite tunes on Internet radio while away from your computer or when your phone battery gets low. This is also the perfect time to run GPS navigation, whether you want to know where you are, what’s around you, how far you’ve run, or whatever you like. Run whatever applications you need to on your Raspberry Pi. Have fun and enjoy :)