Crex24 have replied with the following.
Our current standard listing fee is 0.5 BTC. Integration + BTC market.
Each additional market + 0.1 BTC fee.
Available markets: BTC/ETH/FIAT markets (USD,EUR,RUB,CNY,JPY)
I'm going through the listing process of setting up an account and topping up the balance to 0.5 BTC, also considering a USD listing. If anyone is interested in contributing please PM me.