At the end of the day, a teleprompter is a pellicle mirror reflecting scrolling text from one side, allowing you to shoot through it from the other to give the illusion that the on-camera talent isn't reading. It works well, and you can even build one yourself for a few dollars. But the first high-quality, well-designed prompter and inexpensive prompter I've seen (for use with tablets and smartphones) is called the PRomptBox. At $139 (B&H), it's not only inexpensive -- it's brilliant.