Windshield Crack Needs Fixed! Help!?

Within the past hour I was out driving on the highway and this truck in front of me kicked up a decent sized rock on my windshield, and, of course, cracked it. It was a vertical crack on the far passenger side of the windshield. This crack grew faster than any crack I have ever seen. Within 15 minutes, the crack continued to grow vertically, about 45% up the passenger side of the windshield. It began to taper off to the right a little and currently ends at the far, far edge of the passenger side windshield, once again, not to sound redundant, but 45% of the way up. Money is really tight right now, so I can't replace the windshield, though that would be ideal, so I need a fairly cheap way to prevent it from growing any further, or maybe even a really cheap way to replace it. Thanks for the help.