Be patient. I don't think there is anything yet.
If Spamalot has discounts now, when tourist season is at its peak and many flock to see shows, then there definitely will be something for the winter months, when shows can be a hard sell because of the weather (except around holidays). I would say look in mid-late September to October for something.
Hope that helps!
"We like to snark around here. Sometimes we actually talk about theater...but we try not to let that get in our way." - dramamama611