So that's $1500 prize money if you win 1st and 2nd places in three separate categories, right?
You're quite right, but on the plus side there is no entry fee (unusual for a writing contest). On the other hand, a big minus is that according to the rules all entries become the property of the contest organisers. Don't enter anything unless you are prepared to give up the right ever to sell it anywhere else, therefore.
Also, I feel I should emphasise that this contest is adult-themed, so please don't click through if you are easily offended.
Nick