Yes, there's bulk discounts. The more coins you buy, the more coins you get per dollar. Check the Deposit Coins page: https://www.warzone.com/Coins/Deposit
$5 gets you 500 coins (1 coin/cent) but $100 gets you 10,640 coins (1.064 coins/cent!!!!!!!!!!!!11!)
If you're asking about seasonal discounts or the like, then no. There has never been such a discount to my knowledge.
Edited 3/9/2021 20:09:44