I got a minty complete Soldier Blade for around 2900 yen a couple months ago so they are out there. But I guess you couldnt call it a really cheap game, my mistake. But I occasionally see loosies go for reasonable prices so it's doable if you are patient. I guess it's just one of those titles that is in fairly high demand wherever you are.
Street Fighter, Mr. Heli, R-type, Dungeon Explorer, Legendary Axe I/II and Operation Wolf are all cheap but good titles!