So I've just got a Guitar Hero: World Tour guitar hero controller from ebay (along with the game) and am planning on buying Rock Band 3 next week as it's only £25 from amazon. I know that I need the Rock Band disc to get the songs from the original game, and that you need an unused manual code or something for Rock Band 2. However, I have a dilemna: 
NO WHERE IS FRIGGIN' SELLING ROCK BAND 2!
 
So, basically, is there some way to buy a code without having to buy a new, unused copy of the game. Because I cannot find the damn thing anywhere (in the UK btw).
 
Cheers

NO

Where is this code you speak of? I have a copy of Rock Band 2 but there wasn't any sort of code... I don't think. 
 
EDIT: Nevermind, I found it. IT's the same code used for getting those 20 free songs back when RB2 came out. Here is the link explaining, apparently you can just ask EA for a new code. 
http://www.joystiq.com/2010/10/26/rock-band-3-how-to-import-rock-band-2-songs/

" @trophyhunter:  Could you be a bit more clear with you're answer? You speak in such a roundabout way that I struggle to decipher the meaning of your post. "

I actually just went through the same sort of thing. I had Rock Band 1 and 2 on my last system, but I've since switched platform and decided to get Rock Band 3 for Christmas along with some instrument goodies.  
 
I went out and bought a used copy of Rock Band for five bones (since there's no code for the export here), and found both Lego Rock Band and Rock Band 2 new at Best Buy for like twenty bones.