How about providing extra points (e.g. 10% of the total squad cost; 10pts in a 100pt game) that each player can spend on 'bonus' munitions upgrade cards.
I feel they should be a limited resource (discard after use) and more difficult to fire off (spend TL) as is, but just more appealing to take. As 'free' upgrades, I'm sure most players would sprinkle a few in.
Edited by Dice lord