Street prime

I have been looking around and need a small street prime. I have looked at 20, 24, and 28mm. The 20mm is pushing what I want to spend, I have read the 24mm Minolta has some distortion and the 28mm Sony all though a good lens is built cheap. Any thing bigger than 28mm would be to much focal length for what I want on the a77. I will be using it on mostly the a77 but at times the a99. Thoughts?

The Simga primes look physically bigger than I would like as we'll. thanks in advance.