Thanks for the idea. We had considered this a bit before, but we really wanted to try to strike a balance of fairness in the game.
Currently all players start with WS$1,000 to use Spec Ops. On average this turns out to be about 5 free games before you run out of WS$.
We also wanted to try to make it fairly free to play. Meaning that if you're good (i.e. you win a lot or you play Mission Words - these also give you WS$ possibly) you might not have to buy WS$ for a while. This said, I'm probably giving away WS$ too freely, but at the same time I didn't want the game to be like Candy Crush Saga where you are essentially forced into buying stuff.
So it's all for balance. So far it is OK, but we're still in the very early stages of usage. I may get more greedy later if we're not really making any money, but for the time being I wish to build a good reputation of being fair and not forcing people to pay to play.
That said, I can do a couple of things to increase sales if need be. I could increase the cost of playing Spec Ops or decrease the amount that is awarded when you spin the winner bonus wheel.
Also we hope to remove ads altogether if the IAP for WS$ is successful enough. That way the paid version will simply have extra features. I had some more features planned, but I just can't remember them right now.
Good suggestions though, thank you!!