Using the time machine to teleport back to the weapons development page
at the beginning of your turn can let you get another chance to roll the
dice. If you go back enough times, the unit meter might say that you have
0, 4, or 7 credits. This means you now have infinite credits. 
Note: If it does not work after you go back nine or ten times, then it 
most likely will not work that turn; try again during the next turn.