We also need to factor in the training and logistical cost of the 62 soldiers in those 31 Javelin teams versus the 4 in the Abrams.
It's not the greatest cost by any stretch, but the men (and their survival) are the most important part of the equation.
All of FI is available now. The Commonwealth module for FB will be a while, so that's another reason to wait on it.
Speaking of which, always wanted to play both sides of a Peiper campaign with British defenders.