[quote name='Riyonuk']Why is that? And wasn't Halo 2 like the most praised game..ever? Yet it's easier to find than the first one? That just blows my mind.[/quote]
Halo is older, after so long it started coming out as a GOTY edition, and it went platinum hits. Halo 2 is not as old and you can still find the original edition.
You can find a sealed Halo, but it won't be the original one. It'll be GOTY/PH.