Well, go on a server like Classic and Era, and take a look around you.
On Classic, you see a ton of customs, and on Era, you see a ton of expensive guns and customs.
Now, take a look on Classic. Based on what you see, how many people do you estimate to have customs?
I'd say around 2500 or so out of 4000 have customs.
Now, in that 2500, how many people do you think actually farmed for their custom?
I'd say around 500.
Sooo, around 2000 people bought packs. However, let's not forget about holiday and such. On Christmas, people buys LOTS of packs. I've joined spamming/party type of guilds, and every time they speak of packs and iTunes, it's usually in within 50-100+ dollars per wave.
Same to Era. Oh no, it's probably even worse on Era with the guns.
Sooooooo, I'd say they make a lot of money. At least enough to keep the servers alive.

Also, let's not forget the newer players who wants customs. I'd say around 100-150 people or maybe a bit lower get a new custom a day, plus those who wants 2p mounts lol.

I'd just be blunt and say ToonSlab, or whoever's the owner of GraalOnline is, makes around... 500-1000 dollars per day.