Hello,
a fast lens for 300 bucks or less is almost impossible...
Some people like this one:
Tamron SP AF 17-50mm f/2.8 XR Di-II LD ASP IF
Some say it's fantastic, others say it's absolute crap. If you do buy one, buy it without the Optical Stabilization (Tamron calls that VC), because it is cheaper and according to many reviews the non-VC version performs much better.
Again, the reviews of this lens are all over the place, so make sure you check your version in the store before buying.
In my country (Holland), this lens can be bought new for 290 euros. That is roughly 395 US dollars including 19% tax.
If you want to save money and are willing to use a prime, the canon 50mm F1/8 is great! It is the cheapest lens around, but it works very well (for the price you pay). It is only 1/3 of the price of the canon 50mm F1/4 and almost as good.
For a flashgun I prefer the canon 430 EX II. Also 290 euros new here (but second-hand they sometimes go as low as 175-200 euros!).