According to that site, my mentioned games are worth:
-Lunar: Eternal Blue (Sega CD) - 53.88$
-Lunar: Eternal Blue Complete (PS1) - 39.00$
-Lunar: Silver Star Story Complete (PS1) - 48.50$
They are all complete, nothing missing.
And since that site doesn't track PC games, MVP Baseball goes for 60$+ used on amazon, and the cheaper ones are missing some things, while mine is in great condition.
I'd say some games like Skies of Arcadia Legends, Tales of Symphonia or Shadow Hearts: Covenant are also rare, at least the PAL versions.