Month shard?

"Huatimus;884700" wrote:

Level 78 would mean approximately 4 / 5 refreshes a day. That would cost about 100x2+200x2+50x2+100x3 = 1000 crystals a day. Since he is earning approximately 600 crystals a day (500 from arena and extra from daily activities and GW), he is spending about 400 crystals a day. 1 crystal vault is 15000+ crystals, so that would last him more than 30 days. So he's spent less than 2 vaults worth, so a maximum of $200 USD so far.

You're assuming that he doesn't spent anything on chromium pack, gear and maybe more refreshes than those you mentioned. My guess is he's spent more than 200 bucks even though your calculations seem reasonable