Reading up further, it turns out that VRAM is dual-ported RAM, so maybe a stick from an old Mac/PC is a cheaper source than finding the bare ICs, and easier to work with.

Here's a homebrew VGA GPU board for a modular, backplane-based 6502 computer: http://hackaday.com/2013/01/11/veronica-vga-board-finalized/

Here's a self-hosting Propeller computer:

http://propellerpowered.us/index.php?route=product/product&path=25_73&product_id=55

And a FORTH-based 8 bitter:

https://sites.google.com/site/libby8dev/fignition

A different homebrew Kiwi, also 68k (DragonBall SoC)

http://scanlime.org/2011/07/kiwi/

StickOS® BASIC is an entirely MCU-resident patented interactive programming environment

http://www.cpustick.com/