Target's online store has Metroid Prime 3: Corruption listed for pre-order. The best part is that it's listed for $29.99 and of course it's a typo... but, Target is honoring it so far. So, I suggest you hurry up and go to Target's site to pre-order Metroid Prime 3: Corruption. You will only have to pay $30 for the game and that's a really, really good deal. I don't think this applies to their stores too, but it might. Well, what are you waiting for? Go to Target's site, which is here, right now!
[UPDATE] It appears that the actual game page lists the game at its regular price of $49.99. But, some people have called in and have been able to get it at $29.99. I suggest you call.