Yeah 15k is actually a great price for an adult sumo red like that. They can easily fetch 30-40k.. The platinum Asian arowanas reach north of 120-150k. The albino pearl stingrays start at 150k each. The fish game gets ridiculously pricey at that level... Each fish cost way more than the entire setup and cost of maintenance.
I would be pissed if I lost any of those fish to ich lol