To anyone who is interested, I was browsing Yahoo Auctions and found this guy is selling a bunch of Prototype/"Sample" Famicom games. At 5,000 Yen each, they're too expensive for me but maybe someone on here will be interested (a few are unnamed Namco games...)
http://openuser.auctions.yahoo.co.jp/jp/user/ecoshop0?alocale=0jp&mode=2&apg=8
Interesting!
I am a bit suspicious about a couple of them though, like this demo model of Hot Scramble seems to be nothing more than a regular copy of that game (worth about 200 yen or so) with the word 見本 (sample) written on it:
http://page13.auctions.yahoo.co.jp/jp/auction/r114305695
Same with this copy of Ninja Kun
http://page8.auctions.yahoo.co.jp/jp/auction/h188679729
From beta-tester/codeveloper? ???
Labels looks old/aged, but printed with matrix(?) printer.