I was searching on ebay and came across this:

[url=http://cgi.ebay.com/Sonic-The-Hedgehog-Sega-GENESIS-RARE-BETA-TEST-GAME-WOW_W0QQitemZ280303055274QQcmdZViewItemQQptZVideo_Games_Games?hash=item280303055274&amp;_trksid=p3911.c0.m14&amp;_trkparms=72%3A570|66%3A2|65%3A12|39%3A1|240%3A1318]Sonic 1 Proto[/url]

Its selling for $499.99 and apparently the seller even wrote to SEGA to ask if it was a real proto but failed to actually open up the cart and see whats inside...