you'll probably never find a definitive list of "rare or OOP" discs.
start with CE plastic. work from there.
Speaking of CE discs...picked up a nice Leopard and a Eagle at a garage sale the other day for $3 each...heck of a deal I thought!! Thanks Deano!!
Actually you got them for 2 natty lites and 3 old style beers. I'm always happy to give sweet deals. I have some more garage sale junk like CE valks?