[650D / t4i] beginner would like a new, light lens for one-month trip

Hi there,

I really need some help here.

I own a 650D since four months or so, and I'm liking it a good deal.

In January I will be travelling one month (in SEA) and, besides a bag to pack the stuff (but that is easier to research), I would like to have another lens.

Right now I own the 18-55 kit lens, which is pretty fair to me.

But recently I got interested in seeing wide angle photographs, so I was thinking to buy a (super) wide angle lens, as I believe it can be very useful in situations of crooked streets, or huge landscapes.

Problem is, I don't know where to start to look for a lens.

And I don't have all this much time left to approach this huge learning curve by myself.

My requirements are for the lens to be

• cheap (less than 100 awesome, less than 200 is oké too. A really great lens is available for 300? I can consider it, if I can appreciate that greatness, considering my low skills
• light
• it would be awesome if it is a WA - medium zoom, so I could live the 18-55 home; travelling light is a must!
• second hand is completely fine

If you could at least give me some directions, for example, brands on which to focus my attention; or to forget about this because decent WA lenses for this price do not exist on Earth.... it will be much, much appreciated!

thank you!