I hope this isn't too nitpicky, but the error message when trying to buy something that you don't have enough currency for comes across potentially triggering (in a minor way) at times.
I know it'll be a little bit more coding, but I suggest changing it to “You do not have enough [insert currency here] for this item.”
Maybe it's just me, but being in a financially difficult time personally seeing “You cannot afford that.” whenever I refresh too many times in Arena hit a nerve. My initial response was “Yeah, I'm poor, I get it thanks”
While this is definitely a minor thing, I do feel like the wording could be tweaked a bit to be more courteous and less harsh for some folk.