Well, call me crazy, but...
I just learned that your average "Husky" bike pump, (sold by the air compressors in Home Depot), can reach all the way up to 300 PSI.
It's ridiculous... the hose on the pump expands to around 1-1/2 times it's original diameter. You have to put your entire weight on the handle and actually jump to get the last few pumps out of it. Firing it is a completely different ball game as well. I made a video below, but it really doesn't do the sound and feeling any justice. It actually sounds like a .38 or 9mm going off, and the marble is only visible for a second. Here's some stuffs:
<center><img src="http://www.markfh11q.net/images/300psi.jpg"></center>
<center><a HREF="http://s10.photobucket.com/albums/a123/markfh11q/?action=view¤t=DSCN0318.flv"><img src="http://i10.photobucket.com/albums/a123/markfh11q/th_DSCN0318.jpg"></A></center>
