See below for a Color Chart which displays Jackson Kayaks 2015 Standard Colors and also colors that may be used to create your own custom color. Custom colors comes with an up charge. Please know that mixing some colors does come out different than they would seem to. See your local Jackson Kayak Dealer to order. 
Do you know the average additional cost and wait time for a custom Jackson Kayak?
Typically it is a 200 dollar up-charge you would have to check with your local dealer. It will be about 4-6 weeks lead time to be shipped to your dealers door as the factory will custom make the kayak. Do know that not all customs come out to your vision. They do try their best though!