Here is a list of all the skins in the game pretty much, including the unlockable ones.  Not mentioned are the Liquid Metal Lancer which you get with the purchase of the Season Pass.  The bottom 22 skins though, are attainable by purchasing them on Xbox Live on Day 1 of release (September 20th).  I’m thinking maybe 800 Microsoft Points for all those bottom skins but hopefully it more like 120 Microsoft Points since they are just weapon skins!

Gold Onyx Skin Attained by Reaching the Highest Level in Multiplayer

Unlocks:
Chrome
Gold
Gold Omen
Crimson Omen- Hammerburst/Retro/Gnasher/SOS from doing things in-game.
Flame
Team Insignia
Onyx

DLC:
Infected Omen
Liquid Metal
Liquid Green

Paid:
Garish
Artic Camo
Desert Digital
Desert Camo
Deadly Cute
Childs Play
Blood
Electric
Flower
Haze
Imulsion
Rainbow
Team Pulse
Oil Slick
Ocean
Thunderstorm
Team Distress
Team Metal
Tiger Stripe
Jungle Digital
Tribal
Urban Digital

Earth Defense Force gets new DLC with two new weapon packs. The DLC contains the Pounds of Pain! The EDF Battle Armor Weapons Pack, and the Death From Above! The EDF Jet Armor Weapons Pack, and is available for $2.99 on the PSN Store and 240 MS points on Xbox Live. Both the DLC gets 15 weapons including all sort of missile launchers.

GamingBolt reviewed the game and gave it a 7.5/10 score, which you can check out here.

5. SCAR-H

Modern Warfare 2

A beastly weapon, on all accounts.

The SCAR-H is a fantastic weapon. Highly  used in MW2 multiplayer, and often equipped with a Red Dot Site, this thing is unstoppable. With high accuracy, long range and dishing out a lot of damage, what more can you want?

4. Cannons

Empire Total War

Cannons can be devastating, not only to flesh and blood, but moral.

There are few things more demoralising than a massive cannon barrage from a well placed artillery battery. And if you find the round shot pretty destructive, wait until you get a hold of quicklime. That stuff is evil, it acts like toxic gas that lingers on the battlefield.

3. Hidden Blade

Assassins Creed II

Who doesn't want a pointy blade up their sleeve?

The Hidden Blade makes a reappearance from the original AC with devastating power. With the ability to swiftly and silently make your kills, the Hidden Blade is a very valuable asset. It may not be big, but I bet it certainly feels painful when an assassin is sticking it your throat.

2. Needler

Halo 3: ODST

Spiky.

When you get hold of a weapon that shoots out exploding spikes at a rapid pace, you know it’s badass. Not only do the large spikes themselves do a fair bit of damage on impact, they then explode, causing considerable damage to the erm… recipient- and anyone standing near them.

1. Electricity Gun

Killzone 2

There are few things more satisfying than liquidating someone with the Electricity Gun. There is a reason why you only get to use this awesome gun a few times- its bloody powerful. It takes but a second to cook your opponents with this high-voltage weapon.