Rob Cai has shared a fantastic tutorial on how to build an Arduino-based BASIC computer, and it will only cost you a few dollars. All you’ll need is a pair of Arduinos, a PS2 port for the keyboard, and a VGA port for video output to a monitor.
Build Your Own Arduino-Based BASIC Computer for Just a Few Dollars - Video Part 2
In this Instructables I will show how to build a retro 8-bit computer running BASIC, by means of two Arduino and few other components.