Retrocomputing

I have been lusting after a Apple 1 Replica for the past month or so, however, not much time due to my Japanese studies, work and family. Then I started thinking about tiny modern CPU (PIC, AVR, etc) systems that are built with the sole purpose of being a computer to code on, thing Altair, Apple 1, etc. There aren't many requirements, 4-8k memory, small display (single row, 30-some characters, like the one on a TI cc-40), keyboard interface (cheat: and use a usb interface?), simple monitor software and the key component: BASIC. Anyone know of such a setup? Nonetheless, someday I would like to build one: to relive old memories of my youth hacking basic and have a system that I understand completely (Jack Crenshaw mentioned that he loved a system wherein he understood or built all parts, and I couldn't agree more).