White Label FX Broker for Currenex? First question you have to answer is: - what do you think how much daily/monthly volume your FX Brokerage will generate? Currenex has one dangerous feature: their passive limit order logic when marking up raw spreads for your end clients. Currenex Tier2 usually don´t ask for "fixed set up costs" like the clowns at MetaTrader....usually you pay volume bassed, monthly commissions or a mark up on the spread....
What trading software will be on client side? Keeping all liquidity in one basket is not a good idea better to try aggregate it from several LP's if you don't want to be bombarded with clients complaints on how they got spreads widened to 100 pips during Friday close
Currenex is aggregating liqudity from more than 100 banks/non-banks/market makers and so forth. Why would you even bother about "Friday´s close"? My Currenex platform has Top of the Book liquidity of over 120 Million in EUR/USD almost around the clock/24h/5 days a week. And what do you mean by "What trading software will be on client side?" - I don´t get the intention of that question?
Platforms like MT4 or Ctrader may have different license costs what I think you need to price in as well.