I am probably going somewhere untrodden, but.....
How about seizing the future and adopting a crypto-currency as a payment method for FSP?
It would give players opportunity to mine/trade/buy their FSP. It is possible even with a simple CPU(GPU are obviously more profitable) if we chose the right currency. I can give a simple setup guide to do this.
For example, there is a UK based crypto with a huge community following it, Electroneum #ETN.
Not only would we encourage the current game base to find a passive additional source for purchasing FSP, we would also be putting the game in front of 1000`s of #ETN community members who are looking for an additional purpose for their currency.
Just an idea to move with the times....... Thoughts?