This was originally suggested by beeper23 in another thread, but it got no attention aside from 3 likes, so I decided to repost it here.
Basically, we think it would be a good idea to allow users to use coins to further discount the daily sale. In other words, if there’s a $10 game on sale for 50% off, people could spend 2000 coins to get 20% off of the discounted price and only pay $4. I imagine that you buy keys in bulk in order to discount them as much as you do, so you might also have to put a limit on the amount it can be discounted (e.g. if you bought 1000 keys for $4000, then $4 would be the lowest price anyone could get).