So, I was doing some champion upgrades in the tavern with brews.  Then this...

I started leveling up champions with the regular cost of 4,000 (or maybe it was 4,500, can't remember) coins per brew to level up champions.  In the middle of leveling up champions, the cost per brew went from the 4,000 or 4,500 it normally is, way up to 7,000!  I thought something has to be wrong here.  I don't remember ever seeing this increase, but figured maybe it was because of the rank or level of the champion, so I tried it on other champions.  Everyone was the same - 7,000 coins to level them up with one brew.