Another option for retro-gaming hardware is Andre LaMothe's XGameStation line of DIY kits.
Looks like they now have a "Chameleon" line of kits, in both 8- and 16-bit flavors, which are similar to Arduino or BASIC Stamp systems.
I have not personally used these, but they appear to be pretty cool.
Enjoy.
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Pete
Disclaimer: "These opinions are my own, though for a small fee they be yours too." -- Dave Haynie