You'll want something with decent performance in lower light (ie: have a lower f number). For your budget, there aren't many good low-light options. Instead of the 18-55, perhaps look at the Tamron 17-50 f/2.8. The Canon 50mm f/1.8 would also be a nice choice, as it's sharp, extremely cheap, and fast. If you haven't yet, check out the review section and read up on these lenses.