I need a recommendation for a new portrait lens for a T2i.
I initially bought the 50mm 1.8 about a year ago and initially loved it (with some limitations) for taking pictures of my kids and family. But now with my little guy becoming more mobile and starting to walk/run the focus on the lens is just not able to keep up with him. I'm finding the lens amost useless to me now.
I am a beginner in the field of digital photography and don't find the time to become better. I'm hoping in a few years when the kids are bigger I will have more time to improve my skills but for now I just need gear that is easy to use.

So I need a lens that is quicker to focus and I'm not sure if the 50mm 1.4 is it. The 85mm sounds like a good lens but on a crop-sensor it will probably not work for me. Then there are some 35mm options, but then price becomes an issue...
Even though $300-400 is considered cheap, it makes me flinch. What options do you recommend? Will the 50mm 1.4 work for me or do I need to look at something else?

Thanks!