Cracked screen by setting it face down on the desk topic

I just looked at my phone a few minutes ago and saw that the bottom part of my screen had one crack going from left to right. It's below the soft keys, so it's not a big deal unless it spreads, which it probably will with any drop at all. It was fine this morning. I must have set it face down on the desk and something hard and small was between the desk and my phone because there is a pen-head sized spot right along the crack. Just sucks to see after all this time of not dropping it, it cracks when I set it down on something.

Any advice? Where can I get the cheapest replacement screen? Should I just sell it and buy another? Wait for a new phone that's coming out soon?

Thanks