softball

I have a canon rebel EOS T2i . i actually love the camera and the 50 mm lens that was already on it. i was asked to take photos for my daughters softball travel ball team for their website. so i am going to need a different lens. i was wondering a decent lens to start with that would allow me to capture pictures at home plate and in the outfield. i do not want to spend more than $400.00. i know that is not much for a good lens for sports. so any suggestions will be appreciated. i also have a nikon d90 i use for portraits. so any suggestions for that i will take to. thanks