Not exactly a discount, but I found it's maybe possible to double-dip on the Kobo VIP Super Points.
I bought myself a gift card to use up a prepaid credit card. I noticed during checkout about receiving Super Points for this. I then used the store credit from that gift card to purchase a few books. I also got Super Points.
Considering they
fixed the loophole of using store credit to buy gift cards, I'm surprised this is a thing.
EDIT: I'm not seeing the purchase of the gift card accounted for on the Points History page - so I think maybe I was mistaken.