You don't "need" to play 1 and 2 to enjoy Metroid Prime 3. You do get the backstory on what's happening if you play the first two, but it has it's own beginning and end and you won't really be lost too much as to the story.

Look up the games you want on Amazon. Find out which is the least expensive used. Go to the VGChartz (Amazon) store and buy that game. Keep doing that until you buy all the games you want.

Metroid Prime 3 and No More Heroes absolutely.
(>'.')>

just buy no more heroes new though. It's 20-30 bucks now, and suda is a fledgeling genius. He's somebody that deserves support for his work, and No More Heroes is just a cult hit without major sales to back it up. Obviously enough sales for him to be happy and warrant a sequel, but still not very good sales.

Control + F = Okami

No returns.

What the fuck!  Nobody has yet mentioned Okami?!

Buy Okami. If you enjoy Zelda at all, you'll enjoy Okami.

No More Heroes. D:

Buy Wii Play - it comes with a controller (so is a $10 game) It has some awesome fun stuff that your girlfriend will like, and it has a sweet shooting game and tank battle that you might like

Name your favorite games on other systems, and name what your girlfriend likes to do.

Definitely agree with the Metroid Prime 3 suggestions. Awesome, awesome game. No More Heroes, also.

My personal suggestion would be Tales of Symphonia: Dawn of the New World. =D

One of the most overlooked awesome games of the year, and only $6!