TriX wrote:
What body do you have - crop or full frame? A “nifty fifty” is fine on a crop, and if low light is a priority, the EF 50 f1.4 would be a good choice. Alternately, the 50 f2.5 Macro is an excellent lens for the $. Slower, but quite sharp, will double as a Macro (1:2) and can provide 1:1 with the addition of the life size converter in the future. For a full frame (and a longer portrait lens on a crop body) the EF 85 f1.8 is hard to beat. All of these are in the $300 range.
I love the 85mm f/1.8 but it would probably be better on a full frame than a crop body for what you want to shoot. It would have a narrow field of view on your crop body. But it is very sharp and fast focusing and a nice portrait lens...