You can find the product at Pepboys or AutoZone. You can find it mostly anywhere they sell leather interior products. I know the saddle is "not leather" but the cleaners that are intended to clean leather are less harsh on materials they come in contact with.
If you can't find it, I also use Quick Detailer by Meguire's for not just the seat, for the entire bike frame too. The mission statement is not to use anything too abrasive causing fading or colour loss.
Cheers.

Click to Enlarge Photo
By the way, have you had any issues with the narrow profile of the saddle wearing on the inner thighs of your shorts?
Here's my thread fix here pertaining to the saddle in question specifically.