I'm considering buying a microphone.

First of all, I can't afford a thousand-dollar mic. The local music shop has a couple of deals and I'd like to know if anyone has any thoughts on them.

This is what I'll use the mics for:

Voiceovers
Usually simple voiceovers. Maybe sometimes loud screaming stuff, maybe whispers. ADR, or just plain voiceovers.

Effects recording
I will probably be recording a lot of the sound effects for movies, including the occasional bit of foley, or crunching sounds, slurping sounds, stuff like that. A lot of what I do has fantasy or horror elements in it, as well as special and weird ambient sounds in rooms.

So...

One deal the local music store offers is the following mic for $100:
www.google.com/search

The other deal is a dual-mic pack for $80:
www.google.com/search

Suggestions? Observations? Recommendations?