Hello all, Typhon here. Free Comic Book Day is coming up this Saturday (5/5/12), and many comic shops around the world are not only giving away free books but having great sales as well. In keeping with the celebration of the new film, I have put together a list of some Avengers trades I feel are worth a look. Some are on here because they are classics, some because they are essential ,some because they are fun, and some because they are all of the above. Keep in my, these are (obviously) just my honest opinion. With that said, here we go:

1.
Essential Avengers Volumes 1-8: The perfect starting point. These 8 books hold the first 184 issues and 8 Annuals of the book that started it all (as well as crossover issues like Defenders). Yes, they are in black and white. Yes, the quality is up and down especially the last half of Vol #2, all of #3 and the opening of #4 when the big 3 are largely absent and the team consists mostly of Pym, Panther, Hawkeye, Wasp, Quicksilver, and Scarlet Witch. Without any heavy hitters, the foes were just above street level and not too compelling. It does ramp way up in Vol #4 when the big 3 return. Still, the art is beautiful, and the ride is worth it. Plus you get great stories like Avengers\Defenders War, Kree-Skrull War, and the Korvac Saga.
Each volume is priced at $19.99 US, but earlier editions run for $16 or $17.
2.
Omnibus\Masterworks: For you fans of color, this is your (pricier) alternative. The first Omnibus holds the issues #1-30 with fully restored coloring. It includes a cover collection, the letter pages (along with Stan's answers) for each issue, and other extras in a beautiful hardcover edition.
It runs $99.99. There are 11 hardcover Masterworks editions and 4 paperback editions out as well.
The HC run for about $60 and the PB for $25. While these are in color, each book only contains 10 issues while the b&W Essential books hold 20-24 issues.

3.
Kree\Skrull War: The original space epic. The Kree and Skrull empires declare war on each other with Earth caught in the middle. With a glaxy at stake, Cap, Iron Man, and Thor lead the Avengers into space to take on two alien civilizations. Written by Roy Thomas.
The current HC runs for $34.99, but lower priced soft covers can be found easily. 
4.
The Korvac Saga: The Avengers take on a being who not only wants to destroy the universe but has the power to do it without much effort. By Roger Stern and George Perez, this collection also features Ultron, the Guardians of the Galaxy, and Cap and Iron Man coming to blows.
The soft cover runs for $24.99.
5.
The Contest: Death! The Grandmaster! THE YEAR 1982! Relive the epic CONTEST OF CHAMPIONS in this hc featuring the Avengers East locked in deadly combat with the IM friendly Avengers West. Collecting CONTEST OF CHAMPIONS #1-3, WEST COAST AVENGERS ANNUAL #2 and AVENGERS ANNUAL #16.
It runs for $24.99.
6.
Avengers Prime: Cap, Thor and Iron Man together again for the first time since that one time last time a long time ago. When these three buds get together, it's all dragons, talking ogres, and Hellcat sex jokes. Good times.
The soft cover runs for $16.99