Just do it the cheap, easy and lazy way and grab some old geode or C3 based thin clients off ebay and hook up to a cheap and efficient lcd and use about 15w for the whole thing. They already have netboot built in as the default, so there is only server side to set up for the most part. Granted they don't have that cool oldschool flavor.
Yes, you could do that but then you don't get the glowing green screen which is quite pretty in my opinion.
Also regarding the person who posted (and deleted) about the Raspberry Pi, it would make the terminal just like a personal PC as the Pi is small and easily concealed.
As a bonus you get a keyboard and display on a single USB port! (use a powered hub though)
I happen to know that it can be also done in Debian which is a good fit for the Pi.
It is hard to find a real CRT terminal for under $70.
I got mine for about $50 and often do some C++ and Lisp programming when bored. Vi works well Emacs required a bit of setup (But Emacs is what I like).
I'm currently writing a vt100 display library as you can see on the screen there.
From a programmer's perspective, it is absurdly simple to control the cursor and display on these devices.
To move the cursor and set screen attributes, you simply send it plain text ASCII codes from stdin.
Any programming language that writes text output can be used to drive a graphic display on the terminal via simple sequences of letters.
You can see my very very early C++ source code here (consult zinc.h)
https://github.com/RyanBurnside/libzinc