yay do the workers get discounted the same way?
Nope, workers are just retrained as marines, no discounts involved. This is normal since it wouldn't be realistic if you trained 1 worker into 2 marines... that would be cloning

However, if you hire the marines with credits say you have 50% bonus, you train 1 mil marines using 0.5 mil credits. If the marines escape in pods, you now have 1 mil workers that you can retrain as marines 1 for 1. So indirectly, you can say marine resupply bonus does play a role in it too...